Of the lenses I got basically for free over a year ago and had never sent to clean, I kept 3 and sent them to Eric Hendrickson. Just got them back yesterday:
K 50 1.2
M 100 2.8
M 150 3.5
The M 150 3.5 in particular was not in good shape, so much fungus I couldn't shoot with it. But now I can tell it's a pretty sharp lens even wide open, despite reports to the contrary! At least my copy is, so I'm glad I got it cleaned. Last year I had already agreed to give it basically for free to a forum member (it was for 15 dollars if I recall) but because of Covid the other person backed out... now I'm glad he did
The K 50 1.2 and M 100 2.8 were known quantities, I have been using them as the bit of fungus they had, did not affect the images, or so it seemed. Let's see if I can tell a difference.
For my standards I paid quite a bit of money for this cleaning (210 dollars plus shipping both ways- more than I paid for either one of my SMC Limiteds!), but I think these particular lenses are worth it.