Try our new info resource - "Aladdin's Cave" (Main menu)Just added a separate link to Ash's Dropbox thread (shortcut)
I never thought of it at the time - afterwards I did wonder if a couple of really close fitting bolts with a thick washers could be inserted on each side then give them a good thump with a lump hammer. The bolt might stop the tube from distorting alternate on each side in the hope of breaking the rust layer after thorough soaking in penetrating oil. Even better if the tube was threaded to take the bolts?
Not sure on the exact sizes of the original rubber sleeving but this may be a starting point .. they do many other sizes.https://www.ebay.co.uk/itm/285006013277