Some years ago, around Hitchin I think, engineering works took place and it was decided that rather than have rail replacement buses, trains would run instead but coast with pantographs lowered for the short section required, and it would all be a lot less hassle for the passengers.
An excellent idea.
Until a 365 came along. On a 365, when you dropped the pantograph the unit went into DC mode, and they happened to have an AWS receiver for DC mode as well as a seperate one for AC mode. The unit went into DC mode and did the self-test for the DC AWS receiver, but because it hadn't been maintained (why would it need to be on the AC Great Northern line?) the Driver was unable to cancel it despite jabbing the button increasingly frantically as the seconds ticked by, and the train came to a juddering halt right in the dead section.
It took an age to get everyone evacuated off - the unit couldn't be rescued unless the wires were switched back on, and it ruined the service for the day.
365s were never allowed to Coast with pantographs lowered ever again.
Anyway, (lack of) maintenance or removal of, DC equipment was a bigger problem for them being sent back to 3rd rail land than you might think. The shoes were the least of the problems.