Metamec Quartz Clock with Plastic Kienzle Mechanism - Refurbishment/Service

I came across an old Metamec clock in a charity shop which I liked the look of. I noted to the sales person that the clock was about one hour slow. This was last year (2024) about a week before the end of October when the clocks were due to change from BST back to GMT. i.e. go back an hour (I get this wrong in the video). The sales person claimed that "..our technician must have put the clock back early." But who changes a clock early? I knew what the reason was of course...it was running slow. And indeed it would lose minutes in an hour and eventually after a few hours it would grind to a halt, with the battery still with plenty of life in it. One look at the back of the clock told you that it had not had a service in a very long time, if ever. Here I attempt to do this and get it running as a quartz clock should. i.e. very accurately.