Vintage Synth Repair

Hello all,

I just joined this board.
I recently bought a Kurzweil K2000 and am experiencing strange problems.
This Mix outputs are very low and the Headphone outs are very high, cliping at 
medium volume.
A quick search on google revealed the following:
"This was a common problem on early K2000's. Later units had a 
protection board installed (also available as a low cost upgrade for 
older systems). Problem, as I recall, was that static electricity or 
floating ground problems could blow the output transistors when 
pluggin/unplugging cables to the unit.
There is a transistor on every output that mutes the output when you first 
turn on the keyboard.  Static electricity can fry these.  If you plug in an 
audio cable to the K2000, THEN plug that cable into an amp, chances are you 
will short the tip of the plug to the chassis of the amp.  This will destroy 
the transistor.
The remedy is to replace the transistor." 

I was wondering if there was any K2K owners on this list who would be familiar 
with this issue and how to fix it.

Thanks in advance

Laurent