Well if you've got a working one, and the transistors (with heatsinks?) normally run very hot in that one, then it's maybe less of a concern on one you're trying to fix. Although if they do normally run that hot, then maybe why they can seem to be prone to failure.
If the regulators are running cool-enough with heatsinks fitted, then that shows they don't appear to be overloaded at least. From this internal-photo, on a past thread (re-attached here), it does seem that all the regulators are actually originally-heatsinked
- Although it's a bit too low resolution to find the mentioned ones:
https://www.vintage-radio.net/forum/...8&d=1468530387