when I go to my local Triumph guru and asked about this he just grabbed the gear , rummaged around , found a drift and beat it out and replcaed it in a simlar way.
Everythings fine and I guess the bloke knows how these things fit and how much force can be applied. I just know if I used his approach on the various parts I've taken to him Ii'd have just a pileof bits.
If youre doing it y'self I'd use a little heat and steady applied pressure: slowly, slowly catchy monkey.
Leave the heavy full on approach to them that know.