I’m occasionally asked about maintenance of split-frame chassis, but in reality there is not much maintenance required. Unlike wiper pickups, split axle pickups don’t wear out, or go out of adjustment.
For lubrication, I use the smallest amount of Peco electrolube. Over a period this will get a bit dirty, and needs flushing out, and this can be done most easily with a spray can of electrical switchcleaner (from Maplins for example).
I’ve only ever had to rebuild a chassis for other reasons, motor failure for example, and in two cases because the gearbox mechanism was too noisy. In all these cases I’ve checked the axles for pitting (caused by electrochemical erosion) but have found no evidence.
I’ve had the occasional breakage of the wires from tyre to axle, which has required removal of a wheel, and subsequent refitting and quartering. I can only recall one failure of a split axle, and this was where I had tried using Milliput instead of Araldite to glue the axle components together, on the grounds that it’s easier to get Milliput into the socket than Araldite. I haven’t tried this again.
I’ve had occasional problems with short-circuiting, including one where the original insulation was provided (inadvertantly) by a few layers of paint inside a wheel arch. Once this wore off where the tyre touched around sharpish turnouts I started to get mysterious shorting which took a while to find and fix.
Tyres have to be kept clean as with any pick up system. I used to use a fibreglass brush, but I now use a wire brush in a mini-drill to remove major crud, followed with a wipe over with some meths. If you can release the worm wheel so that the wheels can turn freely, the wire brush can be applied while the chassis is being pushed along the track - very quick and easy, and no pickups to get bent or broken.
Apart from that, - maintenance? - what maintenance?