Stuck sash window

[FunnyOrca]

Hello,

Any advice much appreciated!

We had the window frames (internal) painted over the summer. One of them is open the tiniest crack at the top and is firmly stuck! It wasn’t really noticeable until the winter winds started. It is stuck on a slight diagonal and we can’t get it to move up or down! The lock mechanism still works, but is very tight as it is not coming down far enough.

Any advice for getting it moving again?

Sorry, just to add, they have not been painted shut! This is all the advice I can find on Google. I think it’s a swelling/alignment problem!

Are these wooden windows?
i have 16 windows in my house and we had to renovate in three tranches.
If it’s really damp outside windows become more temperamental so a sticky window is even more troublesome. My 6ft 4 joiner popped in and was strong enough to dislodge then re-greased them. Not sure what with though… could have been oil, or wax or WD40. But they’ve been running a treat since.