Homebrew PCBs

I bought an Epson C84 to convert for direct printing.  It was 
adverstised as having a clogged print head.  I have read several 
articles on how to unclog the print head.  So far I have been 
unsuccessful, but it is still early in my process.

The thought occured to me, however, that maybe the electronics driving 
the print head are bad.  How can I determine if the print head is in 
fact clogged or if it is something else.  Are there any voltages going 
to the print head that I can check during the print cycle?