After a long shared voyage through time, I noticed that the rails on my faithful BPM bellows and the ball of the Manfrotto head were 'catching' ever so slightly, and wondered what I could do about it. There did seem to be some kind of grease on the Manfrotto ball, in which particles had involved themselves, while the bellows rails had signs of superficial corrosion here and there. I wiped a smear of the Manfrotto goop onto a microscope slide, and found it to contain two sorts of inclusions - graphite particles, and other irregular objects including silica, hair fragments, and cells that were probably shed human skin.
I flushed out the joint with paint thinner, followed by methylated spirits, until I was satisfied that all the dirty grease was gone, but this left me with the problem of what best to replace it with. I didn't want to replace one lot of grease with another to act as flypaper for micro particulates, so I thought to try pure PTFE powder alone.
My first attempt was not a success. The PTFE powder came in a little puffer, and fine though the dust was, it wasn't fine enough to get between the ball and the socket of the Manfrotto 168, and was even more useless on the BPM bellows rails.
There are dozens of different PTFE lubricants out there, many having PTFE only as an additive to an oil-based lubricant. At last I found one that contained nothing but micronized PTFE in a highly volatile base that would evaporate in seconds leaving a very thin film of PTFE behind it.
I applied a couple of quick squirts of "Tefluibe" to the Manfrotto ball, worked the socket for a few seconds to spread the film, gave it another quick squirt for luck, and that was it. All 'catching' gone without recourse to noxious greases, which will always try to leave their rightful place and make their presence felt where they are least wanted.
Back to the BPM bellows rails, I attacked the superficial spots of surface corrosion with ordinary toothpaste, rubbing it round and round for a few minutes with a small piece of sponge until the corrosion was gone and all was shiny and smooth. A couple of squirts of "Teflube" on the rails, and the bellows moved backwards and forwards just as smoothly as they did when I first bought them more than 30 years ago. Success!