RPM meter - looks great but doesn't work!



I own a 2-door Charade 86, recond. '93. My car doesn't cause much problem, but its RPM meter teases me everytime I get into the drivers seat. I've seen this issue in a couple of charades', but no one is as concerned as I am to resolve it.

Actually, the problem is, if the car is parked in the sun for long hours or is driven for 30 minutes or so at night (in a hot weather), the RPM needle starts to motion. This is very surprising behaviour. Even if I pump the full accelarator, the needle hardly crosses level 2, but thankfully, it atleast picks to that level. Yet another surprise; if I get my car serviced at this time, the RPM will go to sleep for next 3/4 months, & after this much time, it starts to motion - teasing all over again.

Please note I have got RPM checked by a person known as car-electrician, but he was unable to fix it. On the other hand, Daihatsu here doesn't provide services for car models prior to 2000.

Please help drivers!