Bench Testing

440 Mike said
Ammeter nuts were loose on the posts also, cleaned and snugged up

Be carefully tightening ( or loosening) the nuts. I destroyed a perfectly good gauge because the nuts twisted the posts.

Since then I use two nuts as jam nuts to hold the post tight while loosening / tightening the nuts.

I also had an Ammeter that the posts were twisted enough that the insides were shorted to the housing