What I’m thinking is that you have a bad connection that rubs on the terminal. When you pinch it, it causes a solid, non-moving connection that eliminates the noise. Too little insulation will not cause a problem unless you mean that the insulation is stripped from a certain point and bare wire is touching the terminal. I’m pretty sure I know what you're saying but I’m not 100%.
And to AzGrower, I completely understand where you are coming from. I do not take you as an ***, just someone who is confident in what they say. When I comment on something you say I am not necessarily trying to prove you wrong, just trying to either show a different side of an argument or trying to stimulate intelligent conversation/debate over a disputed or misunderstood opinion.
Get me?