Hi Jock,
the plastic V is afaik only a press fit. But it's stubborn, both if you want to remove it, and if you want to mount it.
On the other hand, painting the case—most of the time—makes it worse that if it has patina, from use.
Varnish usually only emphasizes irregularities, unless you sand-smooth over-sand-smooth over, and ABS plastic is not the best material on which to do that.
If in doubt, before ruining the case, I'd try to paint on the inside of the lower portion of the case. If the result kind of meets your expectations, go ahead, if not, better not do it. I had quite a few customers on service tickets who had to admit that they ruined their radios, with a paint job ...
—Eddi
Born to fly ...
forced to work.