I'm a fan of switching ps kits for classic games.. But not for Gottliebs, as with some very basic mods and a rebuild your original ps works much better. I've used an arcadeshop one in my old qbert.. Hated it.. Knocker was weak, as it lowers the voltage to 12v instead of 30v which is needed.
Riptor sells the rebuild kits, he accepts Paypal.. Hell, if you can't rebuild it yourself ask him to or I'll even do it. I've got (3) rebuilt Gottlieb ps in qberts and mad planets and they have been working for years now!
I know someone is gonna argue this, but its just my opinion.