Remove the unit and take it for repair, nobody is going to mess with it further than that.
You will only be doing what Vendolator would be doing to their equipment, repair leak, add drier and refill.
They would have also replaced that 50 year old brittle wiring harness and added fresh new quiet fan motors.
And like John said, while it is out is a good time to clean the messiest areas of the machine.
That's a nice original there Jonathan, we're glad you are concerned about originality but you want it to be safe too.
Any particular type of shop you'd recommend? seems most refrigeration guys come to you now a days..