Gauge is voltage driven, if the voltage is down it will throw it off a little. Quick way to check to see if the generator is working is to place a voltmeter across the battery terminals. 12.6 (or higher)is normal battery voltage when all the cells are working. When the engine is running it should be 13.8 to 14 VDC. If not, no output to the battery. There is a fuse on the alternator (an AC generator) that blows on these cars. Run a search because a few in the group have replaced theirs.
