Years ago I got a number of surplus double sprockets from Princess Auto, I cut one in half and welded each sprocket to 1/2" bolts. The bolt at the operator side is 4" long , I cut the head off after welding the sprocket to the bolt and installed a handle I got out of the old Delta parts box.
It was quite tight to start with, a couple squirts of thick gear oil helped a lot.
I started the remote bolt lock 1/2 a turn first, before I started the the handle lock. this to insure the remote side locks first, a good tug on the handle snugs up both sides.