Prints getting worse - PETG

Hi

I am printing a whole load of parts in PETG.
All started well, then the right hand extruder started playing up and now doesn't work...
OK, over to the very little used left hand extruder then.

That is now starting to fail as well.
I have had to dial the speed of the PETG printing right down to 15mm/s to get anywhere near a decent print... which results in madly long print times. This one is somewhere like 30 hours, which is mad.

As you can see, this print is having real layer or under-extruding issues. It's a new roll of filament, but the old roll one started doing it too.
Fitted a new nozzle - but that has not fixed it.

This printer 'used' to be bullet proof, but now has become super unreliable.
Doesn't help that spare parts are almost non-existent or extortionately priced.

Not sure if the hot end is no longer staying to temp or what. I did have an episode of the extruder gear slipping (clicking), so I swapped it with the non-working right hand extruder.
Try finding spares for those! AliExpress came to the rescue in the end, as FlashForge didn't want to know.

Any ideas as to what may be slowing changing? The settings are the same as I always used.
What settings are you guys using for PETG?

Nozzle jammed this morning. 20 mins with a blowtorch and just cannot get it unblocked. This was a new nozzle+PTFE tube 1 week ago.
I have come to the conclusion that the Creator Pro is basically only any good at PLA.
I don't the the nozzles can cope with PETG.