Bob, I used lots of Q-tips (dry, wet, then dry) and visually inspected. Before running the first test the alcohol seemed to dissolve some varnish so I kept it in the mix. The surfaces looked clean enough for government work. Presumably, wiping without the alky would have done as good a job for what I wanted to know. If you like, consider the isopropyl scrub a bonus. It is possible some residual lube escaped the soft dry cotton in the final step but that's life. Did I say scientific? :^)