did you pull it out and lube it up? hit it with WD40, and clean off some of the crap on the back?
I had a bit of an issue with mine when i first bought it, the mechanism a tthe back was covered with crud and was really hard to moove etc. Hit it up with WD40, and a toothbrush or etc, and that should be the go. (parts cleaner would work well too.)
I'm sure there is a way to pull them apart, although probably a bit complex. Maybe it'd be best to find another and pop it in?
Just my 2C
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