Lots of different vibes flying around in this thread...
In my case, I bought a completed TT xox off the yahoo auction here in Japan, after reading the forums here and very carefully considering what I was possibly getting myself into, and after a number of email conversations with the seller, in which it was made clear that as long as the case was unopened, there was a one-year guarantee. At first I was quite satisfied with the unit overall, but after a short time, I noticed that the tuning was not quite right. Specifically, only a few notes out of the whole range were out of tune, which was an unusual problem. I contacted the seller, but was told it was most likely an analog issue—temperature sensitive beasts as they are, etc. But my 303 did not go out of tune for the year I had it before it was smashed under a 20-space rack during a studio move, nor did it suffer from similar 'these notes only' out of tune issues. The seller did reassure me that it was just a calibration problem and that the one-year guarantee would remain in effect even if I opened the case to calibrate it. I started a thread on the forums here about the calibration dilemma, and received excellent advice from many people, to which I am still grateful, and although I thought I had managed to solve the problem, sadly it persists.
My frustration was all the more compounded after hearing that a fellow electronic mayhem creator here in Osaka obtained a completed xox off the yahoo auction, but it was put together by a solo builder, and has absolutely no tuning or calibration problems whatsoever.
Also, when I did open the case to attempt to calibrate the VCO tuning and range, I was shocked at the truly haphazard soldering I found on certain parts of the pcb. It is almost as if different people were put in charge of populating different sections of the pcb—some are quite clean, others are just a mess with sloppy solder, cold joints (which I fixed), and even untrimmed legs on some of the components! WTF!?!?!
My original purpose for buying a completed xox was because I had no experience soldering or testing/tuning/troubleshooting/using a multimeter etc. Now, that is not the case. I have put together a number of easy DIY things (LED circuits and atari punks), and recently have built and sold some 40106-based drone/psycho 'synths' (two of which were featured on matrixsynth, google heterodyne space explorer and one of the first results will be mine, the evil red satanophonic hellsynth). Now I feel I can handle putting a xox together, and just ordered a kit from willzyx, who thinks my tuning dilemma may in fact be a thermistor problem, and offered to throw a set in for free with my order! How cool is that?
Some people may have had positive experiences with TT, but I am NOT one of them.