If the caps are bad, there could be an increased load on the transformer causing it to vibrate.
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You are right to replace the caps. Hopefully the caps you ordered are not merely electrically the same but "designer" ie better sounding. Cheap caps do indeed sound cheap. Swapping out caps for higher quality is one of the surest, easiest mods you can make. Probably second only to diodes.
Anyway, swapping them out would be a good time to check those transformers. Some are bolted straight to the chassis. If that is the case you might want to try putting O-rings or rubber washers between the transformers and the chassis. Or if the VTL already has them they will be hard, maybe even cracked after 30 years, so there you go.
Littelfuse makes a copper alloy/tin plate holder(click on the pic to see the pdf/download). Acme fuse holders are silver-plated and inexpensive: https://www.partsconnexion.com/fuses-holders-clips.html .