the kind of board that needs calibrating.........................................with a hammer!!!!!!!!!

It's the type of board that the lm339 is ok but the 74hctxxx that is behind the lm339 is stuffed 
Then I noticed that a lot of the insert lamps are not working, then I notice that one of the led's next to the insert lamp fuse is out. fuse checks out fine & it has the correct voltage on the test point. turns out the led is faulty but of course changing an led won't fix the inserts being out. and there are no faulty transistors for the inserts. I haven't found out yet what is causing the problem.