Ok thanks .will try another rectifier
Well, take a close look at the work you performed when taking the alternator apart again. Make sure all the connections are good, that you didn't put an insulating washer somewhere it shouldn't be, etc.
IMO, the bulb is dim because the resistance on the circuit is high. I can't imagine that they are going to take back the rectifier you've already bought so it's in your own best interest to make sure there is nothing else that could be causing this issue. If you disconnected any wire, any connection, you owe it to yourself to make sure that is not the cause of the problem.
Is there a replaceable regulator or is it integrated into the rectifier? I'm asking because I don't know what the ground path for the bulb is. I mentioned the rectifier before because that's the part you said you replaced. The rectifier changes AC current to DC. The regulator controls the rate of charging.
As I said, I don't know the path to ground for the bulb. I would double check all internal connections before replacing anything more.
I like that you repaired instead of replaced. Not too many people do that anymore. Many times, rebuilt alternators can be of far lesser quality than the component you returned as a core.