Replaced a coil and immediately when powered up it chattered like a mad thing. I think I had two problems. First the coil wouldn't hold in, the gap was much larger than comparable coils, even though the replacement coil was exactly the same length as the original.

Even with the spring disconnected it would not latch in, to test I stuck an extra washer at the other end of the coil, this brought the gap down from 2mm to 1mm, which is the same as the other coils of this type. The picture shows the coil before adding the washer. After adding the washer the coil latches - sadly all the time which is why the first one burnt out.That's the second problem, but I'm chasing down the reason.

A question - should I be bending slightly the bass finger to hold the plate in closer tot eh coil - this will increase the spring tension, whereas putting in a washer does not change the spring tension.  Any advise or comments appreciated. Thanks.

Also does anyone have any tips - the pun is intentional - on what to use as the nylon bits in the end of chime box plungers - mine have melted!