TDHofstetter

No way around that. Like all other spot putties I know about, it's acetone-based... and acetone dissolves polystyrene. That means that it bonds to the model like gangbusters, though.

There's also a huge difference between a freshly dipped (cleaned) carburetor's color and the color of a carburetor that's been on a hot engine for the last thirty thousand miles, complete with gasoline vapor and leakage... and even more so if that engine has a slight oil leak at, say, the front crank seal.

I may predate you here. The red/white pre-inhalant-freakout Testors tube stuff was in fact solvent cement with some quantity of polystyrene already dissolved into it to make it gloppy. It absolutely melted the plastic surfaces it got onto and wrecked them if it got onto places where it should not go; there was no way to remove it like you can always remove glues.