Adjusting counterweight on Loricraft RCM

I recently bought a second hand Loricraft PRC3 record cleaning machine, but it seems the previous owner has not set it up correctly since sometimes a little knot of thread is built up under the nozzle while cleaning a record. The suction power however seems strong and sufficient, so I think there is too much downforce on the arm/nozzle.

Does anyone know how to adjust the counterweight? There is a tiny hole in the weight, but I don't see a screw inside. Do I need a set of precision screwdrivers or a different tool?

Also, I'd like to check if there is vaseline on the magnet. I cannot find a manual online on how to remove the arm. Any tips?

Many Thanks,

The counterweight on my PRC3 has a small screw in the hole. From memory, a small Allen key was the tool to loosen/tighten it. Of course, being British-made, they're liable to have used whatever screw was lying about! ;-)

Many users (including me) advise adjusting downforce so that "VTF" is effectively zero, ie, so that the arm with the suction pump turned OFF simply floats level. This is contrary to the instructions in the manual. Oh well... I prefer what works.

Suction alone provides all the force needed to keep the nozzle on a spinning record. Addtional downforce from the arm can cause marking of some vinyl (I've seen it happen) and may increase the tendency for the thread to back up at the nozzle, as you've experienced.

I've never removed my arm, sorry. Speaking of vaseline, putting a bit on the hose fittings before sliding the hoses on improves air-tightness and suction.

User tip: when applying liquid between vacuum sweeps, leave the pump turned on with the nozzle hanging off the back of the machine "sucking air". This helps stop the brass tube mucking up.
I own a PRC4 and agree with everything Doug just wrote. The arm can be lifted straight up and out. It takes some force because of the magnet pulling it down. The brass collar around the base of the arm remains on the deck. My counterweight is attached to the armtube with a locking set screw that can be loosened with an allen wrench. I can't remember if it is Metric or English.

I put a tiny film of Vaseline on the magnet under the arm. It seemed to help with the movement across the LP. I have set my VTF to zero but I still occasionally get a small bundle of thread at the suction head of the arm only when it is moving from the LP label to the outside, not when it goes from the outside to the label.

I do a double suction when removing the water rinse by starting the arm at the outside of the LP. It moves to the label, then I pick up the arm and place it on the other side of the spindle at the label and it continues to the outside of the LP. This assures that it is absolutely dry.

I placed a small rubber washer on top of the spool of thread to keep it from rotating during use. I also put plumber's thread tape on the threads of the glass jar. This helps with air leaks and increases suction pressure slightly.

Congratulations, it's a nice machine.
Thank you so much for your responses and all the tips Doug and Peter!

I will give it a try asap and will let you know how it get on.
In addition to the many useful suggestions above do check Yip Mint's site as he has some interesting ideas eg putting a bit of vaseline on the jar collar where the lid comes in contact is a huge plus otherwise it can be difficult to prise open the jar.
Like Peter I also use the brass arm of my PRC 4 from lp edge to label then crossing the spindle/record clamp(I have an old Michel Gyro clamp)from the label to outer edge. Unlike Peter I use this routine with the enzyme cleaner as also for the distilled water rinse.
IME the thread curling occurs because the white nozzle gets wet creating extra friction for the thread. As Doug says one way of avoiding this is to keep the vacuum pump on with the nozzle in its resting place(the PRC 4 has a brass receptacle) otherwise let the arm dangle on the side.
Congratulations on the Loricraft. Its a great RCM.
Thanks for the additonal info and congrats Pradeep.

I lowered the counterweight and it seems the issue with the curling of thread under the nozzle is almost gone. It happened once during cleaning of appr 15 records.

Maybe another cause that contributed to my problem was that the thread became too wet because I was using too much fluid (I literally flooded the record) and/or I did not wait long enough to have a part of the fluid evaporated. I am now using less liquid, but make sure that it is still wet all over, then wait about 1 minute and dry the record from the label outwards. ANd leave the pump on between the cleaning steps.

I did some test recordings before and after the cleaning and the result is really amazing. Less pops and crackle and much more detail (dynamics) in the music. What a great machine!
The brush is dry when you start to clean your first record, here you need the
most fluid, with the next record and the following ones you need less fluid for
the cleaning. After a few records you will get the right experience for it.

Point nozzle design and its result is simple school knowledge (Physics -->
ouch) transferred to High End :-) I know, this is not fair but ...
Using too much fluid doesn't necessarily clean better. If the fluid isn't down inside the grooves in contact with contaminants it isn't really doing anything but making a mess. :-)

Agree with Peter and Pradeep regarding a double vacuum sweep, especially for the final rinse. I do it just as Peter described.

Agree with Syntax regarding fluid usage on the first side being greater than on subsequent sides, as some base amount of each fluid is needed to wet whatever brush you're using. One advantage of the brushes sold by AIVS is that they don't hold much fluid... less cross-contamination and less fluid waste. It's useless for scrubbing but it's debatable how much use scrubbing is anyway.

Glad your're enjoying! IME, clicks and pops are best eliminated by use of an enzyme-based solution as the first step. Greater detail and micro-dynamics are a result of really thorough cleaning and rinsing. Two rinses with *very* pure water will bare the tiniest modulations and let you hear deeper into a recording than you ever thought possible. That's the true test of a clean groove, not how quiet it is. In fact, a truly clean groove is often slightly noisier than an almost clean one... but the additional musical information is more than worth it. When I clean and replay a visitor's record he's blown away by music he never heard before, not by how quiet it is between the notes. :-)