If you have some time on your hands, there are some old amateur astronomy books on telescope making that have info on how to make small lenses. You can make a lap form fitted to the front surface of your lens and polish it yourself.

The book title is Amateur Telescope Making by Albert Ingalls, published by Scientific American. There are three volumes. Books II and III have information on small lens making for eyepieces. The polishing info should work.

I bought the set from an online used book seller. Some of this information might be downloadable from the internet.

If a lens has been exposed to water, sometimes it develops a thin layer of alkaline mineral deposits on the outside surface that cannot be cleaned off with the usual glass cleaners. An acid cleaner might work. Try warm vinegar first, followed by hydrochloric acid if that doesn't work. Vinegar has worked for me to clean these deposits off old microscope slides that had been in storage for many decades. Windex and ammonia didn't work at all.