Pictures will help, but I would suspect the 4 1N4004 diodes in the ultrasonic power supply side have gone short circuit.
Well I got some time over Xmas to have a look at this power supply and I checked every component off the board. I appreciate I probably didn't need to do that but I looked at the exercise as a learning and practice opportunity, and I'm glad i did it.
Unfortunately due to my limited skills I managed to break a trace on the board so had that problem to overcome too. I'm pleased to report that ultrasonic power has been restored by the replacement of two diodes.
A sincere thank you for your help SeanB it is appreciated.