Citizen Calibre 5700 capacitor

Hi Folks.
I'm looking for some advice before I purchase a replacement capacitor for my Citizen calibre 5700 Eco drive watch.
I have had the watch for 12+ years.
A couple of weeks ago I noticed that it was doing the double tick indicating low charge.
This watch usually resides on a north facing window sill along with some others.
I moved it to a south facing window sill during daytime and when dark placed it in front of an LED torch for some hours.
This I repeated for a week.
It did the trick. The double tick went and the watch kept good time until yesterday when I noticed it was 10 minutes slow but still ticking normally.
Can I assume that the capacitor needs replacing or could there be some other problem.
Thanks in advance for any help given.
John B.

Probably the cap, as easy to change as a regular cell, I did this a few weeks ago to a Eco Drive, I think you need a MT920 cap, about £20 on eBay, but do your research for the particular calibre.

As Jase has said - try cousins for one
Probably be about the same price but you can pop your watch details into the search and it will give you the correct cap

Thanks for the replies.
Capacitor ordered and I'll see how things go after fitting and charging.

Nice one, it will come fully charged.