91 GTi 8V Temp Sensor issues and heater fan issues among others

I just picked up a 91 GTi for a winter beater and the heater fan quits. If you apply pressure to the bottom of the fan it will spin, and this trik is starting to fail too. I was wondering if these were re-buildable in any way(ya know, clean the brushes, etc., as the replacement is more than I want to spend on a cheap beater car.
Also, it's eating up temp sensors which control the gauge and the fan(Ithink), any hints on why this is?

Oh BTW, the Oil buzzer goes off after driving for about 20 minutes when you hold it steady below 2200 RPM. Not really an issue since if you change RPM it stops. Work is only 25 minutes away so no big deal, but I thinnk I should fix it.
Thanks in advance

bad fans might be eating the sensors. i say check the wires for the cooling fan system, most people just hotwire a switch because the fans dont work automatically like they should.

for the oil pressure, replace the sensor on the side of the head, its about 12.00 and the one on the oil cooler about 15.00.

if that doesnt fix the problem you problably need a new oil pump (common for 100k mile plus cars)