Vintage Simmons Drums (UK) Users Group

Hi guys
I've finally got round to testing my SDSV modules using the 1V inputs. I don't yet have cables to trigger from my SDS9 pads. 
I used the audio out from a synth to trigger. All fine apart from the toms in slots 5 and 6. Other modules are being triggered instead of those taking the input. 
Is this a module problem or possibly a chassis problem?
Do any of you guys offer servicing? I could maybe do with somebody tweaking it who knows what they are doing! I'm in the UK btw. 
Thanks. Dave