I had to do both on my 86.

If you have the money new is better in the long run, and it sort of depends on how much your time and effort you want to spend polishing old lens vs the cost of replacing with new. A good polish is one of those things where if the lenses are in good shape you can get a decent result. You have to remove the lens either way to fix the moisture leak issue. There are four plastic bumps on the lens surface that will get in the way when you are polishing.

Inga arrived at my house with a major moisture issue in both lens. Did the polish thing on left side and replaced the other side with new since that one was in sad shape. The lens on left side had been replaced when Inga earned her deer tag in about 1994. When she arrived at my house a few years later, found that both lens were leaking about the same. After replacing the lens on the older right side bucket, found it looked almost new. Replaced the lens on the left side a couple of months later so they sort of matched. Still have both up of them in the parts stash just in case an ECode ever gets cracked. They were both still clear and dry when they went in the parts tub this past spring.

Couple of tips, do not wipe the sliver on the backs, the silver will come off and reduce how much light goes down range. If you find moisture still in the buckets, a hair dryer will make short work of it. Clean dry surfaces along with a good even bead are the key to a good seal IMOH. I did also put the lens down on a cloth and wrapped a couple of big rubber bands around the lens until the RTV dried. Be gentle, the plastic on the back gets pretty brittle and it is easy to break or crack. I used Dave Shannon's write up as my spiritual guide by the way.

For the sealant, I used electrical grade RTV and never had a problem with the seal. Electrical Grade does not have a lot of the solvents that other types of RTV have. You get less out gassing and it will not damage the lens or the bucket. Some of that cheap can make a mess and even melt plastic.

I used the stuff from GE but several companies make an equivalent. This is not a product endorsement so maybe I can get a pass from one of our two SAM’s and not get a thumb down.

Good Luck and Regards,

Paul