my battery light is on most of the time [occasionally goes off then on again] do I just replace alternator or get parts to fix it .Felicia 1.9d 1997

It could well be just a voltage regulator (or the carbon brushes) that is at fault . These can be replaced for about £25. You can do a simple voltage check. Check battery voltage without engine running and about half an hour after engine was stopped.Voltage should be about 12.6 / 12.7 V . With engine running and all the "consumers" ( headlights, rear window heater, etc on ) measure voltage at battery. This should be about 14V or above with engine revs at about 2000rpm.. If its much less than this either the voltage regulator on the alternator, or the alternator itself is faulty. You can remove the regulator and check that the minm. brush length is not below the recommended minm. length ( Haynes manual may have this info.) . Brush length should be such that the brush spring is compressed by about 6mm min. when regulator is mounted on to alternator.

As above except, the regulator was £12 on JoRily last time I looked.