F1 chrony problem

I got an old F1 green chrony as part of a purchase. It has a display and an on off switch. When I turn it on the numbers keep turning over. If I cover up the slots the display shows 0000. As soon as I uncover either one the display starts turning over again.
if I put a flat battery in the display shows 0.000 as I would expect it should.
The chrony was covered in wood dust, so I will pull it apart and clean it.
Does this sound like it's a no hope or is there something I can do?