

You won’t be able to go perpendicular, the rectangular cross section will be larger than the mouth of the jar at the corners. They can get it parallel and try to slide it out the way it went in, but it might pull a vacuum and get stuck.
They are likely going to need to break the jar to save the weight. No big loss, it happens.







So you might be able to save both the jar and the weight here.
Finish the pickles, empty the jar and clean it out so you just have the jar with the weight inside. Dry it out and put like a drop of vegetable oil around the weight.
Put the whole jar in the freezer, get it super cold, more importantly get the air inside of it super cold.
While it’s cold get the weight in the mouth of the jar and get it trying to come out, it should want to pull a vacuum. Once it does, just warm the jar and the air inside of it up to room temperature. The pressure from the air warming up should pop the weight right out, if not use a hair dryer.