Yeah, kantleak water manifolds, never fail bearings etc.
Those early kantleaks, made by the anderson brass company were almost all plastic.
If it helps, this is the foam Lippert uses when they do repairs.
And I got this dispenser along with the spray cleaner.
I find it easier to let the foam do its thing and then use a hacksaw blade to trim. I'll use 2" blue painters tape for any location I want no residue.
https://www.ebay.com/itm/Touch-N-Sea...item5961c16a7c
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1