Check that the pivot holes arent all wallowed out in your alternator they sometimes need to be bushed. But you have to know why did it break in the first place.

2003 Civic Alternator Bracket Top Bolt Honda Civic Forum
Alternator bracket bolt broken. This meant either pulling the head to extract or deal with the 4 inches of available space to. Allmost looked like jb weld. I read this in an internal honda tech bulletin. I just tested my alternator a few weeks ago and it was good so id rather not buy a new one. This bracket should not be subjected to large forces. Can you get at the broken off bolt with a dremel.
The ear is definitely broken off the engine not the alternator. The compressible bushings on the forward brackets do a good job of holding things in place and there was enough thread left to get the bottom bracket bolt to bite. I think you may have excessive tension or may be misalignment in the belt. Yeah you can tig weld it but it need to be professionally done it is a very difficult job as the alignment is very important. Its best for bolts 14 or larger and the shorter the better but it sure will surprise you. I was able to get the alternator back in place.
Alternator bolt broken vw mkiv a4 tdis ve and pd if the thing holding it in is a broken bolt id try to hold the broken bolt and get the nut off of it then try to push it out in an area where theres clearance. The bolt had quite a bit of material in the threads. Apparently it must have been the alternator bracket and case shaking around before. This method works great. Belt tensioner bolt broke flush with bracket how can i remove this bolt you can use a centre punch to start loosening the broken boltjust keep tapping it in the undo directiona bit of patience and perserverance is required here. Two of the alternator bracket bolts broke off in the head of my 1992 e350 ambulance.
How to remove a broken off bolt. If so you could use a cut off blade to cut a groove in the end of the bolt and then unscrew it with a flat blade screwdriver. The rear right mounting ear on the alternator case threaded for the long bolt is cracked also. The problem with the constant alternator bracket stay breaking is most likely from an improperly torqued lower alternator bolt.