Hi. Reviving several inherited clocks has been one of my projects during lockdown, although mine are older Black Forest movements; despite their antiquity the actual value is low, so I was inclined to go down the diy route (I also looked at second hand movements which were super cheap, but figured that their springs were probably exhausted). It sounds like your spring has ‘gone’ and while they are easy to replace, getting the barrels in and out of the frame is easier said than done, and as I found winding them into a barrel a challenge. Rewinding springs is not for the faint-hearted so if it is a matter of changing barrels so much the better. My top tip is to photograph everything and lay out parts on a polystyrene board. Most of my clocks have spent a great apart of their life stopped (one memorably banished to the loft after its gathering pallet slipped and it awoke the entire household by chiming constantly one night) so I have not felt the need to re-bush anything although if it is apart, that would be the perfect time.