I bought one of these many years ago.  I was never happy with the pigtails it produced, so after I got my first ROS, it's been sitting in the (well somewhere).  After reading all the glowing reviews of it in the 1980s FWW, I decided to get it out and give it another try.  As you might expect, the foam pad was completely disintegrated.  Knowing the PC is essentially a dying breed, I just pulled out some felt pad, punched some holes in it and will give it a try.  The pad was stuck to a metal frame so I'll be using that on the felt pad.  

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I have one of those, also. Not sure where it is now but I always hated changing the sandpaper using that little "key"

You should be able to purchase another pad..

Nothing like the buzz sound of metal on wood while sanding inside corners, Doooh!

We used those sanders in the 80’s -90’s until the ROS appeared., there still kept around in shops to get corners in between lacquer coats..

I got the pad cleaned off, put on a new felt pad, and gave it a test run with some new sandpaper.   May have gotten it's place back