Agree. Unless the filter caps are malfuctioning, just leave them
Changing the coupling caps could theoreticaly change (improve) the tone, but in this case 1) the stock polyester film caps are decent & 2) the choices available with lead spacing that will fit the board are limited.
When I did my JCA22H, I used Orange Drop 225P's , which are also polyester film and fit the board, but I only changed them because I was changing the values.
OD 715P / 716P will fit, but they are polypropylene film, and are cleaner / brighter than polyester. Those will def change the sound of the amp, but it's impossible to know if it will necessarily be better or not. I've rarely encountered a scenario in a high gain build where swapping the caps to 715P / 716P has been an improvement, but YMMV. The only exception would be to use a pair of 715/716's for PI coupling caps to pass the preamp signal to the power tubes as cleanly as possible.
You could also look at WIMA, which are available in both polyester and polyprop, but getting all the lead spacings right could be tricky.
I think your best bet is to just leave it alone unless you want to change values. Swapping out all the caps for the same values of a different brand is probably not worth the effort in this case.
