Mike, when I repaired electronics (20 years military), they told us not to use a pencil eraser to clean electrical contacts. Said it would leave a residue. Told use to use a "Ruby Red" eraser (or one other I forget the name) ... because they would not leave a thin residue like pencil eraser ... and to always clean after with alcohol. You're using alcohol in your process, so meh. Just thought I'd share an anecdote.
Sheesh ... I worked around computers since 1967 ... the technicians & engineers always cleaned the boards contacts with pencil erasers when trouble shooting faulty connections ... not even swabbing them with alky when done. I do prefer the greenish colored erasers better ... they seem to work faster (less spinning). Maybe they are a tad more abrasive.