[Test-Equipment] Triplett 321-PL meter covers

[Robert Nickels]

A strange question I know, but does anyone know the secret to removing 
and (especially) replacing the clear plastic meter cover on a Triplett 
321-PL series analog panel meter?    I know it has to sort-of 
bayonet-onto the metal dial scale but it's proven really difficult and I 
figure there must be a method I haven't stumbled across yet.

Thanks and 73,
Bob W9RAN