I wonder how many folk engage in PM?
I'm a strong believer in the principle of if it ain't broke don't fix it but having lived and worked for several years at Thunder Bay (Canada) I rapidly acquired the habit of periodic preventative maintenance.
Twice a year and at the time that the clocks change I've developed a check list that I run through.
Obviously the external aerials figure high on the list and this year after "Megger-ing) the coax to my 11 m aerial I observed a leakage of just over a meg that simply didn't show on my Avo 8 which was because the voltage applied by a typical Megger is 500 volts rather then the 15volt from an Ago 8.
Quite a few pounds spent on replacing RG 8!
The PM that I've just finished showed up nothing so it was just a case of a new UHF plug, lashings of grease, lots of self amalgamating tape, and the whole thing sprayed with aerosol marine boat varnish along with the bracket mounting.
Indoors a visual inspection of big power supply electolytics to see if any are starting to spew their guts and a clean out of the fan filters of the bits and pieces that have them.
I've installed a separate RCCB (or whatever the current fashion to call them is) and a quick and dirty test of that is well worthwhile.
Then inspection of the ground spike and connections to it.
Maybe I'm just a pernickety SOB but it's surprising what turns up sometimes.
I suspect not enough of us Roger but that's all sound advice!!