"Bob Engelhardt" wrote: (clip) Any ideas? Before I start tearing it
apart, which I'd really rather not do.
^^^^^^^^^^^^^^^^^^^^^
This may be too obvious to mention, but are you sure the tip is free of
obstructions? (Warning: the first time I took mine apart, I didn't know
what to expect, and I lost the electrode.)

BTW, in case you are new to this, the electrode and the tip are
consumables--it's a good idea to keep spares on hand.