210RP One Hundred

Hi Folks
I wonder if some of you out there might be able to help me?
A little while back I acquired the above amp and, seeing as it was over 30 years old, I took it to a local amp tech for re-tubing and a general overhaul. However, after 2 visits to the repair guy and having various failing components replaced (capacitors, resistors etc.) the amp still exhibits an unpleasant and unmusical distortion when playing notes on the bass strings. I have every faith in the repairman but just wondered if anyone out there with specific Music Man experience might be able to shed some light on a possible causes or causes (failing speakers perhaps?).
Also, the amp seems to start breaking up too easy for my liking; gain at 4 or higher and the Hi/Lo switch results in almost no change in output volume or tone and the master volume causes no significant increase in volume in the range 5 to 10 to speak of. Is this normal for these amps?
Any comments or suggestions would be greatly appreciated. Thanks

yeah the gain to volume ratio takes a bit of playing with.best way to remember is gain below volume clean ,gain above volume dirty ,I find mine to be pretty clean at equal settings as well.now speakers play a huge part on breakup,if they are too low a wattage,not engineered for certain applications,wrong impedance....ect.hope this might help.

Thanks Bill, I'll play around with that.
Any more more info on this and some of the other points anyone please?

Check for cross-over distortion. A very common problem in the MM amps with solid state drivers. The output tubes are biased very 'cold' (i.e. low idle current) and if one tube is going into cut-off (so no current is flowing) the result is an annoying ver un-musical distortion.
This sort of distortion is very easy to spot on the oscilloscope.
Cheers,
Lars Verholt