Adjusting counterweight on Loricraft RCM

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.