MG Car Repair: RPM guage, plastic bridge, tach

Question
So many questions I don't know where to start. I have a 1971 MGB. my guess is the block has wither been replaced or rebuilt. It block is painted, and shows no real signs of normal ware the you would expect on a MGB. The Car starts and runs great. And almost everything works on it. The RPM gauge does not. How is this fixed, or where should I check? and off that subject I read the idol speed should be 800rpms? Is that right. It idols well I just dont know what the RPMS are on it. And the clutch is slugish. Once moving the car shifts great. But i have to pump it up to get it to go into reverse, And if I come to a stop at a red light I pump it before putting it into first. I plan on bleeding the slave this weekend. And if possible adjusting the clutch. Any other advice? Thanks

Answer
Hi Joshua,
The tach is powered by a green wire plugged into the back of the tach. You need to confirm that the green wire is powered with the key on. and confirm that the case of the tach is grounded by a black wire on one of the tach mounting ears. The tach signal comes to the tach by a white wire that makes a loop around a plastic bridge with a metal clip over it and held down to the tach by a small nut. Some models had the loop internal and they had two short wires coming from inside and one had a male bullet connector and the other wire had a female bullet connector which connected to two white wires.
Howard