If you can solder, its pretty easy to replace the coupling caps. All point to point wiring on the PL amps and pre amps. The SCRs that come from the factory are ok. They are very reliable, which is why so many use them, but the copper foil caps are much more organic sounding.
There are several sources on the web, soniccraft.com partsconnexion.com that carry them. the Jensen copper foils have an aluminum outer case, the Jupiter copper foils have an outer cardboard or paper case coated in wax.
The PL gear has plenty of ventilation, so have not had a problem with either.
I would send a few before and after pics, but don't think there is an option here to post photos. The cap change out is big improvement over stock, If you like the sound of VAC amps, the caps will get you much closer.
J