Faulty engine hour clock

[NoTies]

One of our yachts at work has an hour clock that only registers about 1/2 the actual hours done. I've had this problem on other boats so knew to replace the clock. WRONG!! It's still doing the same thing and I wasted a couple of hundred bucks (fortunately the boss' money not mine). It's the usual electric clock off the 12V side of the engine alarm circuit. Any ideas on how to troubleshoot it?

[delmarrey]

Maybe the alarm circuit is only working half the time.