is either blown output tubes and/or blown rectifier tubes (and in some cases, this causes a blown quad cap).
The solution is actually quite simple but since I haven't seen anyone post this info (other than a couple posts I made 5 years ago)
I've decided to order a simple kit on my ST70 Tubes4HiFi page.
This will consist of two terminal strips and five fuses. One fuse for the rectifier tube and one fuse for each output tube.
$10 for the kit plus $5 shipping.
Two other new items are for monitoring bias, with either tip jacks to replace the front octal sockets, or blue meters.