Schematic for 210RP One Hundred

Hi Folks
I'm new here!
I just got hold of a Music Man 210RP One Hundred and I am really pleased with the amp which is in remarkable condition for it's age and, generally speaking, sounds wonderful. I bought the amp because I know it is renowned for it's clean headroom. However, I am finding that it starts to break up a little too easily (with the gain at about 3) even with single coil pick ups.
I wondered if you guys could help by offering some general possible causes and in particular I would like to track down a schematic before handing it over to a local amp specialist for a service.
Many thanks in anticipation and congratulations on a great forum; I look forward to posting a good few questions in the future!

The schematics are all available from the website containing this forum: www.musicmanamps.com
Sincerely
Lars Verholt

Thanks Lars. Only just found your reply! I was expecting an email notification from the forum