As said the fan no doubt will be the resistor pack that sits directly on top of the fan and unclips, so easy enough to swap one out.
The rev counter signal comes from the coil/ecu a light green wire, stickiness is not at all uncommon, it might be worth resoldering the connections, but more likely the electronics are starting to pack up, had this countless times, shit quality tbh.
Even when I've had them converted for V8's they are still shit, even though just ben given a clean bill of health.
I'm doing the mondeo rev counter conversion on mine, but unfortunately this won't work on std cossie ignition system.
The rev counters are plentiful enough in the scrappies, no actually thinking about it they are getting bloody rare, have to get me arse down there for some more bits!!
tabetha