Replacing head on a Rk05j

I recently acquired 3 RK05j's that seem to have spent time in a barn as well as having been used by a heavy smoker. I thoroughly cleaned and de-gray-foamed them as well as putting in new absolute filters. The first one came up after cleaning with no issues. Works great. Number two spins up but the initial seek emits a sickening "klang" as the voice coil drives hard to the limit (yes, the graticule lamp is working). Any ideas? The third drive initially had really ugly heads that never cleaned up to my liking. I loaded a disk anyway and for about 5 seconds after the initial head load all was okay. Then I heard the sound of the top head scouring the disk. So I'm thinking of buying replacement heads off of eBay. Apparently these are the heads but not the steel tongues that they mount on. So I have some questions for anyone on the list who may have changed their heads. 1. How hard is it to mount the head in the tongue? Looks like just 2 screws. 2. How hard is it to remove/replace the tongue assembly? Looks like it mounts with a couple of allen screws. 3. How hard is it to align the heads? I don't have a CE pack so I'll just have to use a pack that works okay on the other drive. 4. Any sage advice or whatever? Thanks for any and all help. Marc