ok Donkey, I'm convinced about the tester. Have read about it many times. I am pretty good with tools but lack experience....will let OJT overcome that. I do have a Haynes manual.

I'll look carefully at all connections and, while there, identify any that appear cracked or worn so that I can replace them.

I'm also going to replace the vacuum pump itself within the next six months.

Thanks for pointers.

Nic