Motorcycle Repair: electrical problem, cbr 600, signal installation

Question
I am about to buy my friends 99 cbr 600 F4.  The problem is that he had a friend integrate his blinkers into his tailight.  While doing this all the gaskets do not work.  It does not show rpms, mph, etc.  Do you think that the gaskets could be blown? Or is there something I could look for?  My email is james1007@email.com, thanks for your help.  

Answer
Hi James,

Q:  "...The problem is that he had a friend integrate his blinkers into his tailight. While doing this all the gaskets do not work. It does not show rpms, mph, etc. Do you think that the gaskets could be blown? Or is there something I could look for?..."

A:  What gaskets are you referring to? If "it" meaning the instrument display has no display, check the CDI/ECM. Test it with a known good unit.

I need to investigate the turn signal installation and wiring associated with the modification to accurately diagnose the source of the problem.

Respectfully,
Mark Shively