intermittent charging

[the whole taco]

Surface Pro - from 2017 (when they weren't numbered 1,2,3 ...)
Everything recently fine.
Usually charged in original MS dock.
Recently I bought a 2nd MS Dock for a 2nd location and everything was fine.
But when back in my 1st dock it no longer charges (light is on) and all the peripherals plugged into the dock are working.
Panic when I got a flat battery warning (cause I wasn't expecting it).
Put in the (new) 2nd dock and no charging!
Put in on the original charger and charged up ok.
Back in the 2nd dock and now charges.
But still can't get it to charge in the 1st dock.

What gives?
Can't be the connecter on the 1st dock as it wouldn't charge in the 2nd dock at one stage either?
A dirty contact somewhere? what is good to clean these with?
Some sort of compatibility issue with drivers across docks? Battery drivers?

Any hints appreciated.

edit: just to add, I usually have to restart it to get it to start charging on the 'wall' charger.

 

[interlocutor1980]

Clean connecters with compressed air and alcohol and if the problem persists then it must be a hardware problem.

 

[HelloNNNewman]

Not true that “it must be a hardware problem” if it persists. MS docks have had software issues in the past that have caused problems like this. I’d suggest looking at your recent updates and see if the dock software received any. Try and roll back your settings to a previous time. Check the MS site for any other users experiencing dock issues - it happens. I’ve had it happen in the past and it turned out a software update had affected my dock. Just spitballing some options for you to check.

 

[the whole taco]

Not sure there have been any updates that affect it.
If I have a problem I restart while still in the current dock/charger and it fixes itself.
Future starts in that dock are ok.
If I change to the other doc I may or may not get the problem again (getting it less rarely).
Since the problem started after I got the 2nd dock I am guessing Windows get confused about getting different dock situations.
Both docks are MS, same model.