Sonic Frontiers Line - 1 Volume Control

Has any owner of either a SF Line-1, 2 or 3 preamp experienced problems with the volume control? You may know that the control is in fact an optical shaft encoder.
I have had 3 failures of these units.
First pre-amp just "froze" after a few month's use, and was replaced with a brand new model (as opposed to being repaired).
The second unit also developed similar problems after 2.5 years use, though this time the fault was more severe in that the volume control would inexplicably "ramp-up" to maximum (95.5db) unassisted in any way. Took out a few KT88 tubes on one of my power amps before I get to it - and turn off. The preamp was fitted with a new shaft encoder and "logic" box (behind the fascia) under warrantee in 2000, and was fine until last month when the shaft encoder froze (yet again) after turning on from Standby. The unit will still funtion of course via the remote control, so its NOT the end of the world!Have sourced a replacement encoder and awaiting fitting by local techo.
Purpose of this question is to ask if any other owner of these series of otherwise very fine pre-amps have experienced similar problems?
I know if I say mine is OK it will break. My Line3 did the ramp to max volume when I had my headphones on. OUCH! SF fixed it under warranty which involved a logic change. I don't know if the encoder was replace however.
I have owned the Line 1. The unit went 'out'(cannot be switched on) in the 2nd year of use, and similiar problem arised just after one year. I've also encountered problems with the fancy volume control whereby the unit was not responsive in turning the volume up and down. This problem was somewhat more persistent and the amount of repairs I've done was disconcerting. I've sold the unit mainly due to reliability issues. I've moved on to solid state preamps ever since.
Cicero42, What causes the problem? Did Sonic Frontiers ever give you any explanation? I checked the archives over on AA and only found posts that it was a problem, no causes why. Poor design???

If I could ask you a few questions;
*Do you use the volume knob alot instead of the remote control?
*What is the actual line voltage feeding the preamp. 115V, 120V, 123V, 126V, ?V, ?. Maybe over voltage?
*Did you leave the preamp/s powered up in standby mode 24/7 when not listening. Or did you power them down in the proper procedure completly off? Standby, then off.
*Do you have a problem with static electricity? Getting zapped when touching the preamp/s?

So far I have not had a problem with my Line one.
Here are the answers to my questions,
*I use a programmable Marantz remote control unit to control the volume on the Line One. Very seldom use the knob on the preamp.
*Line voltage 123V.
*I power the preamp down when not in use.
*I do not have a static electricity problem.

Hopefully others will chime in. Maybe there is a common thread for the volume control failure, and not just a design or component flaw.
I have a Line 3, that has a few mods (caps, resistors, wire)

This past winter I had a problem with the volume. Sometimes the unit would go into mute and not come on again. Other times it would go from mute to on and then mute, switching back and forth.
Tried re-powering, fiddled with the remote (changed batteries), changed out all the tubes. Sometimes just leaving it off for several hours would re-set the unit. I was just about ready to send the unit to Chris, when I mentioned the problem to my dealer (they use to carry the SF line), he questioned me about static electricity. I set up a portable humidifier in the room with my equipment, left it over night...have never had the problem since.
I live in an area where the humidity is generally very low, so this may not apply to all, but worth a try
The volumne problem is very common on all SF Line series which use an optical encoder. Sonic Frontiers does not make that encoder, so blame it on the manufacture that makes it.

It's relatively easy to replace, I did mine in less than 2 hours and that was my first job. You can order parts from Frank in SFI or from outside source, but price is very close and Frank is a super nice guy that will guide you thru any problem you might encounter.
The volumne problem is very common on all SF Line series which use an optical encoder. Sonic Frontiers does not make that encoder, so blame it on the manufacture that makes it.
Have you ever heard a reason why it fails?
Is the new one you installed the same as the old, or a new design?
How did you know where to start in the replacing process?
Do you remember how much it cost?
my line 3se have the same trouble,mute the volume and make a "click click click..." mute on mute off sequence.first i think about tubes...but after a short time i realise that the trouble may come from the headphone input.cause when you put the jack on it,the preamp click to mute!!! it may come from the haedphone circuit board!!!.since this time,when i listen music for a long period and want to listen trouble free,.....i put a cotton swab on it!!!!