Hi Mark;
This amp must have spent time in humid locations, so this is what I did;
--removed, bolts and rear cover.
--masked the gap between transformer and the die-cast saddle. Masked the winding on the back side. The transformer was supported to allow a separation from the saddle without disconnection.
--3M abrasive pad was used to remove the rust. Masking of the transformer winding and gap between saddle/chassis is important, as the dust from this operation contained abrasive particles and rust.
--this operation, as well as subsequent cleaning with acetone, removed the paint and oxide finish on the laminations. I had electrical vanish (left over from a torroid transformer dipping project. A small amount of black Tremclad was added to the varnish to return the laminations to their original colour........are you sorry you asked?
Hi "Gepetto";
I guess I have to pull those bolts! I thought I was being meticulous--but I see I have to get up pretty early in the morning to 'out-fanatic' the fanatics! The bolt shanks were quite corroded so they were wire-brushed. Do you think that a generous coating of electrical varnish would be sufficient, along with some washers made from IMAX film (polyester) under the heads and nuts? I believe the laminations are to reduce 'eddy' currents and through-bolts would defeat the purpose; How is this avoided in other transformers, motors etc?---if this was your concern. I don't think there is room for sleeves in the transformer through-holes.
Thanks, Peter