Not to discredit ANY mechanic, but Enfileds are a breed of their own. I've been turning wrenches for 17 years on all kinds of cars, bikes, lawn mowers, tractors and other farm equipment, and my Enfield has stumped me a few times and without the help of this forum (Brother ERC in particular) I may not have ever got the bike running. At least, not as fast as I did. What I'm getting at is if YOUR mechanic hasn't ever worked on an RE, he may not have a clue to what he is doing with YOUR bike (Enfield) and just making random assumptions based on what knowledge he has of other bikes. If this is the case, at this point, you're probably more aware of what the actual problem might be more than your mechanic. Just saying.
Scottie