Bulova Midnight Clipper I think but showing its age, a bit green round the gills , missing the seconds hand , crystal crazed , grubby face and dodgy ‘selfwinding’ lettering, all of which Ihope to get fixed . Still it runs sweetly and keeps time . This style must have have been popular as it seems to have been available for ages. (Some adverts for the Yankee Clipper simply add ‘also available with a black face/dial )
In reply to Yes the back is nice and… by davep
I suspect you'd be able to replace the crystal with a generic crystal of the same outer diameter. Just measure the original as best you can down to 0.1 of a mm and look for a replacement on eBay. If you can match the diameter you should be able to pop the ols one out and friction fit the new one.