Before I order a new powerpack..

[Fed]

Your fuel pump runs on pulses from the crankcase and the pulse limiter is there in case your motor has a backfire, it stops the high pulse from tearing the fuel pump diaphragm.

That won't be the problem if it was blocked the fuel pump wouldn't work.

I'd still be trying the pre-mix spray bottle to test each carby, looking for one with a blocked or partially blocked main jet. Has to be better than pulling 3 carbies apart for no reason.

[tunaticer]

I agree with that Fed, but with the motor nudging its 20th birthday soon I think it is due for a new kit in each carby. Will be spraying some fuel down each throat tomorrow before I test the stator output and coil output. Replacing the new spin-on filter too, possible it may be faulty and collapsed.......Didn't start happening immediately after replacing that filter but maybe 80 hours after replacement......being sealed and non visible there is no way of checking.