[For fun - What is your degree?]

98.6

[nano ampere]

Pico ammeters are available, but they don't give them away.  Stray currents are always a problem when measuring currents this low; you might even need a shielded chamber.  Good luck.

[TENS voltage stabilisation.]

I've never heard of a TENS unit going up to 200 volts; the one I own is considerably below that.  Are you certain this isn't a failure of the unit itself?
Also, does this operate on RF?  Never heard of heterodyning in a TENS unit; only on AM.

[Component symbol... CRT's PCB]

I think that is a symbol for a MOV, metal oxide varistor.  It is a safety device designed to clamp the voltage to a specific value.  In your case, probably to prevent higher than normal voltage getting to the CRT elements--possibly the screen circuit (the screen is one of the grids of the CRT--it does not mean the face of the monitor).
If this part is burned up, it may be impossible to guess what value it would be.  Only the manufacturer would be able to help.