I seriously doubt that you need concern yourself with the filter caps on a Jet City amp. It usually takes years of neglect and actually NOT playing an amp to be concerned with them. There is an alternative to dealing with OLD caps in OLD amps that involve something called "reforming" that sometimes can save them if they are borderline by using a variac.
If the amp is used at least once every month, filter caps can and do last DECADES.
But be warned, voltages in an amp can range from 300V to 500V in the circuit! THERE BE LIGHTINING IN THEM BOTTLES! And it is still there even if the plug is pulled!
If you have ANY qualms about your safety at all, seek a professional to fix any problems other than the tubes.
IMHO, a tube amp sounds so much better than solid state and is worth the investment.
Preamp tubes like the 12AX7, 12AU7 etc usually last forever while the physically bigger power tubes like 6L6gc, 5881 etc wear out the more you drive them, I get about two years life out of them with hard playing. YMMV
BTW, welcome to the DARK SIDE!
When I die, I want to go peacefully in my sleep like my grandfather, not screaming......
like the passengers in his car.