I fear that the "red insulator" is itself part of the leakage problem.... so unless you can totally isolate your restuffing-efforts from electrical contact with the red insulators your leakage-problems will return.
[I've never bothered restuffing the bathtubs in my AR88s; a chunk of single-sided PCB suitably etched and fitted with "turret tags"
https://uk.rs-online.com/web/p/pcb-r...tools/0433589/ makes an ideal platform for attaching axial-leaded modern components. And very much in the spirit of the original AR88 designers when they fitted the big HT-bottom-end bias resistors].