I had an old combat that the end kept coming off of, ( happened to a lot of them) and we glued it back together. It was complained of by the other team that it was an altered bat, and if I used it I would be declared out and possibly tossed out of the league and association for using an altered bat.

I used another bat but researched the rule and as near as I can tell, an altered bat is only one altered to enhance performance, so that grips, tape etc do not qualify. Certainly the bat was not shaved or altered but was repaired, with marine glue to keep the cap on. It had no effect on performance and was a really old bat.. the original grey combat.

Was it an altered bat or not?

In my opinion, no it is not altered. However, ask them if they want to buy you a new bat (if they are wrong) and they can cut it open.

mslacool ... We are familiar with the end cap issue with some of the ComBat bats ... We consider simply gluing the cap back on to be a "repair" and is not "altering" the bat ... Doing so does not enhance the performance of the bat beyond its technical specifications at the time of manufacture ...

can an aftermarket end cap be used if the original cap is broken?

We would think not ... An aftermarket cap by definition is not the same as manufactured by the original bat maker ... If you were to get a replacement from the same manufacturer, for the same bat, we believe that would fall into the category of a repair and would be OK ...