Re: mouth piece question
I have an old alto (not nearly as old, though) on which the newer mouthpieces do not fit well. I use a Conn Eagle mouthpiece I was able to obtain on Ebay which works very well. However, the best way to know what works best is to try different things.
If you go to an instrumental music store, many will let you try various mouthpieces to see what works best for you and the horn. The people there will also be able to tell you whether the horn is worth keeping... though remember they might try to sell you a new horn!
Did the person who did the service not give you any advice on the horn?