The F-6 I acquired lately did not have a key so I ordered a new tumbler with keys. I changed my F-1 without any problems but the F-6 old switch doesn't seem to have a hole in the switch body to where I can depress the plunger to release the cylinder. I see a small horizontal hole but none on the horizontal switch barrel like on the new ignition switches have. I also don't have a key to turn the old tumbler to get it in position to pull it out.
Mine had a brass peg that I thought was a plunger, but was a peg that had to be pulled out. Worst case, to get it turned, slide the spring retainer off -- all the springs and plungers will pop out, you can then turn it with a screwdriver.