RL02 head replacement, disk back online

So after looking at the mess the mice had made of my third RL02 drive I decided it would probably be better to pull the heads and put them in my second drive (the one with the bad top head and plugged filter). Getting heads out was simple, and I decided to put them side to side with the heads in drive 2. The following images show some interesting details. https://i.imgur.com/tcmkUmO.jpg Note that O is original (the heads from drive 2) and the top heads are from drive 3. First, the heads on the third drive were in pretty good shape and looked clean. Under the loupe though I could see some fragments of gunk that needed to be removed. More importantly I did a side view comparison between the bad top head in #2 and the top head in #3: https://i.imgur.com/D6HOxND.jpg This was a really tough picture to take, and you have to zoom in on the heads in the upper right. But what you can clearly see here is that the better head from #3 (left one) is pretty much rectangle shaped while the crashing head from #2 (right one) is shaped like a wedge, with the top part being narrower than the bottom. https://i.imgur.com/fEGuOFE.jpg And of course the filter removed from #2. Note the silicon sludge, I think this is 100% blocked (and was why the drive made a lot of air/wind noises when spun up, the fan was cavitating) This sums it up: I think what happened is the unit was run in a very dirty environment, the absolute air filter plugged up, and the heads don't fly as well without that blast of clean air coming in. So they dragged on the disk, and the ceramic rubbed off (and onto the packs) which led to the eventual disk damage. Moral: Change filters. I cleaned up the #3 heads, put the heads from #3 into unit #2, put the air filter from #3 into #2, and fired it up with the test pack. Goes to ready no problem, will do a full dir/bad with RT11 later this afternoon to see if I still have two errors on the pack. It is interesting to note that the bottom head from drive 2 didn't look too bad, and did not pick up any dirt/oxide from the disk after I replaced the filter. It was probably flying very close to the platter but had just enough airflow to make it fly. Still, I'll put it in the spares pile and think about it for awhile... Otherwise, back in business. I'll be checking the filter on #1 just to be on the safe side. It was my RL02 drive from 30 years ago and was not one of the Solarex ones. Then I'll put fixing this third RL02 on the calendar (will need new wiring, long ribbon cable, filter, heads, and a massive clean-up inside), and start working on restoring my darn RSX11M 4.2 disk packs...