Source Four 36 degree issue

Hi, I'm a new house tech in an old theatre. All the equipment here has been handed down from other theatres over the past decades so I assume I am working with old S4 fixtures/barrels. In my researching I've heard that the 36 degrees, especially old ones, are particularly troublesome but haven't been able to find any solutions for my problem.

Not all, but some, of our 36 degree barrels have this strange double-image issue. Here's a video of just running the barrel. Note the constant double circle, especially when the barrel is pulled out:

And here is a video of attempting to use a shutter with this issue. Note how it's impossible to properly shutter with the barrel out, and how you can even see the shadows from the lens holders:

Any advice is appreciated! They're... usable, but not anywhere near ideal.