Any reason not to use these...

[I'm a beginner!]

Arrived today...

[nholden59]

Hey, I'm also a newbie, but I know those electrolytics for Marshall are usually Dual 50 + 50/500v caps. I think the Panosonics you listed are singles.
JJ also makes those 50 + 50/500v's. They tend to run around $10 US. Last time I bought Jensens at $40 each. I know, probably wasted more money than needed.

[Leo_Gnardo]

For certain electrical contacts, lack of residue is required (relay contacts etc.). That is what contact cleaner is for.
I use contact cleaner and brake cleaner interchangeably. For pots and jacks, I use control cleaner.

For inside the tubes, I use a vacuum cleaner.