[morzh]

When I wash my tuning caps in hot water/dish detergent (so, still has water) - I dump it in as a whole. After that I take it out and let it dry. Then install and do the alignment.

So far I haven't seen anything bad to have happened to the trimmers: yes the water goes under the mica but somehow it always dries with no ill effects and if there were any left I would likely noticed that during the alignment as it would screw it big time.

Now as for the corrosion, the trimmers are made of copper and copper is fine with water - we have copper pipes in houses for both hot and cold, and unless your water is specifically acidic etc, they are fine. Now if you have well water and you know that it corrodes copper pipes in your house, then sure. But in this case you still could use distilled water which is cheap.

In any case, peace of mind is what matter most so if unsure, remove them by all means.