My KOW TSN has seen a lot of usage, and at times I wonder if the lenses are as clean as they can and sould be.  And it's been rained on, so I onder if I should take off the eye-piece and do anything.  Is there a Youtube video or other guidelines on extensive home-based maintanance and cleaning practices?

I use rubbing alcohol and a cotton ball to clean the lens on mine. Rather than dragging the cotton ball across the lens I'll spray the isopropyl with a squirt bottle on stream to wash it away with the scope held parallel to the ground so the alcohol drains off and then use the cotton ball to get the last little bits from the drain side.

Don't let the alcohol sit on there and don't rub at the lens except with the special purpose cloths. I only bother when the dust is heavy, otherwise I'll just blow it off with breath. You could use something like Dawn but I just don't like doing that because then I have to clean off the soapy water with more water and inevitably there's water spots.

I send mine to the manufacturer, they clean it inside and out, inspect for any damage and recharge it..but vortex is good for that stuff...