ok, so had following fault on a club calamari barcrest mpu4.....
upon power up the hopper ran spitting out coins....
then upon test/hopper dump/ normal payout the hopper would not operate giving "obstruction alarm"
the mpu4 was dead prior to this so that got changed straight away.
the fault was the following
open front door, put your hand to back on cabinet above power supply and there is a board 5x6 inches. it has 4 or 5 connectors on it.
4 lines of components, which are 3 pin rectifiers, zenner diode, tiny capacitor and 4 resistors.
i had the first line of components all dead and open circuit. changed the lot and cost me like £5 from cpc....
all working fine now but just have to sort the c435a coin acceptor!
ide like to say thanks for all your help guys....hope this helps other users in future
i have put a pic on here of the offending board