@von Lucky:-

maybe I need to give his lantern and energy a gloss varnish to make it look more 'powery'
@ Zeebeest:- It depends on the figure. If the paint is thick or 'blobby' then yes definitely.
I use acetone nail polish remover. about 10-20 seconds is usually all they need. Then a scrub with soap and a nail brush to get the paint off. I've found that if you leave them too long the plastic goes rubbery. If you let them dry out for a few days they harden up again and feel
Harder than before the stripping. Then you can clean the mould lines off easily.
If the paint isn't thick, I just remove mould lines with a sharp scalpel and a diamond file,
Undercoat with an acrylic spray and then paint as Normal.
One thing:- I used to use an oil based varnish, but over time some started feeling 'sticky'.
Now I only use acrylic varnish and haven't had that problem. I couldn't figure out why some went sticky and others varnished the same didn't. I think that the plastic used in the figures must vary from set to set.
Hope that helps.
Today it's Yellow lantern from 'Arkham Asylum' repainted
Regards
Jim