Bought a roland sc540 with a weak test print for yellow and zero printing coming from lc and lm. cleaned the heads and seemed to be making improvements on all but the lclm. however when replacing ribbon cables to the head i saw a spark. now it wont print anything it will still cut and gives me no error codes. i checked the fuses and they seem to be in good shape also replaced the transistor that controls head power. Not sure where to look next. any advice is much appriciated.