Hi Glenn,
There is plenty of room under the machine to wack the motor end bell.
Should the carbon facing and rubber pump seal be disassembled and cleaned? They'll be reusable? .
You have no choice you have to reuse it, I have, sometimes they are bad, but most of the time they are ok. Just wipe it off and put some zoom spout oil on the carbon seal (side facing the pump housing).
What's a good lube for the start switch plunger?
Get some good automative lithium grease.
Use of Loctite on the impeller screw was recommended
Its not recommend, its REQUIRED! I was going to mention that later in the reassembly process. Loctite comes in two forms. Get the weaker version that can be removed with handtools, not torch necessary.
The most important thing to remember is you have to support the entire mechansim, otherwise its just hanging by its rubber support and this could deform it or worse, rip it if it hangs for too long. Besure to get sometime tall enough to have the mechansim support in the center.