[Heathkit] SB-401 Tuning Knob Insert Replacement?

[OTAKEBI at aol.com]

I just bought an Aluminum tuning knob replacement insert for my  SB-401.
My question is should I remove the old one completely or is it  best to glue 
the new one over the old.
If I have to remove the old insert to do a good job on this restoration do  
any of you know a good way to remove it without damage to the old knob?
I do not see an easy way to do it.
I have an old knob that I have been using to figure a way to do it but it  
can't be removed with ease.
Must be a trick out on the list to do this right.
Thanks in advance,
Dan/N4VET