So you want to know how to move the platen away from the feed rollers? (OR free them?)
There is a lever, I believe on the left that should pull the platen away from the rollers, but if they are melted together, it won't work. Is the mechanism frozen as you said, or the rubber melted together?
If the mechanism is still frozen, it sounds like the rollers are melted to the platen to me.

And anyone wondering, the heat shrink I used is basically a rubber tube thats about 1-2 mm thick. Exactly like rubber. Here is what I just ordered... 25 feet for around $10!
http://www.ebay.com/itm/251658843775?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
Check out their store, they have lots of sizes!

TypewriterGuy wrote:

So you want to know how to move the platen away from the feed rollers? (OR free them?)
There is a lever, I believe on the left that should pull the platen away from the rollers, but if they are melted together, it won't work. Is the mechanism frozen as you said, or the rubber melted together?
If the mechanism is still frozen, it sounds like the rollers are melted to the platen to me.

Sorry... I was not clear, and sorry for trying to hijack your thread. I will take photo and post properly.

It's not melted together - the rollers are actually frozen in the released position. It's the moderately complicated cam shaft arrangement with its multiple bearing surfaces which is mechanically frozen. Does not look rusty, just can't be moved and not sure how to free it.

I did have a machine with the roller melted to platen issue - able to unstick it by just rolling platen, and after cleaning the roller residue off it works fine - for time being. Better I don't disassemble and see what the rollers look like! 

And anyone wondering, the heat shrink I used is basically a rubber tube thats about 1-2 mm thick. Exactly like rubber. Here is what I just ordered... 25 feet for around $10!
http://www.ebay.com/itm/251658843775?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
Check out their store, they have lots of sizes!

Cool! That's cheaper than the stuff I ordered from Amazon, but now I can compare and contrast. 

TypewriterGuy wrote:

I just found 100 feet for the same price, so look around!

Wow. But I bet it doesn't come in cute little pre-cut lengths in a box with compartments, like the overpriced sample I just ordered from Amazon! 

I am going to take a look at my underwood right now. If you need photos, let me know.

Since you don't seem to mind my thread hijacking I'll post some photos here:

Front

Rear

The two parallel shafts with levers and cams 'n such are the heart of the roller release mechanism. It is jammed in the released position. Clearly fixing this is more of an intellectual challenge than a practical repair unless I do something about the feed rollers (like your heat shrink tubing fix), but I like puzzles.

I guess I lied about not being rusty - it's not grossly rusty, but rust is still visible after I've wiped it down repeatedly. If I count correctly there may be up to 12 bearing surface total on the rods! After years of disuse with a tad of moisture around it's not surprising the thing is frozen. So that's the problem: a moderately complex mechanism with multiple frictional surfaces, that I am not inclined to attempt total disassembly on but just want to get moving. So far I've tried liberal amounts of mineral spirits and tapping without result. Half of the bearings may be free but you can't tell which ones: one frozen one will jam all.

What would an experienced restorer do next? Would he or she just bite the bullet and try to tear the thing down completely? Ugh. I am thinking of penetrating oil, as opposed to mere solvent, and heat. Obviously not too much heat with the rubber still nearby, but a moderate amount from a heat gun. What would you try?

Platen is in oddly good condition given the state of everything else.
 

If you still want I can get photos, but I don't really want to be taking off the carriage...
I would keep soaking it, maybe follow where everything goes? Also, try and use some PB Blaster.

My husband bought me a screwdriver that was really helpful for getting stubborn screws unstuck.  The handle is in the shape of a T (I think it's called a T screwdriver).  Anyway, it allows you to get more torque or something.