Ten pounds well spent!...

Turns out that the suspect ultrasonic cleaner wasn't Fairy Liquid after all – couple of hours in the cleaner at 45-50° heat did the job.

The body of the carb took the longest, after about hour I removed it and using a nylon brush I loosen some of the stubborn bits.

The heat makes a vast difference, previously I've allowed the fluid to heat itself i.e. the ultrasonic action would heat it but not to a high temperature.

Looking good - now for the other one.

3 hrs