[codefox1]

Agree, but you should be able to tell if slug is moving by marking the tool you are moving (It should go up or down depending on how you are turning it.) If you are way out of range it could appear to have no effect. You should be able to read the coil resistances without disassembly of the can. You can also check if there are any shorts between primary and secondary windings. The caps inside are a differrent story. If you do tear this down, just replace 'em.