Vintage Simmons Drums (UK) Users Group

Hi everyone first post here just wondering if anyone can help me out.
I've got my brother's SDS9 brain here and it's in pretty poor shape.
Basically only the Bass Drum is producing sound.
I've used both the tap buttons and the auto demonstrate functions.
None of the trigger LEDs for the other drums are working.
Could anyone recommend a starting point for this?
Was looking at getting schematics from musicparts - can anyone vouch for the quality?  Or better still send some free ones :-)
Anyway many thanks 
Stevie