If I am to trim it and respool, is there a tool to use for that? Or does anyone have tips for getting the winding tension right?

On another note, my backspace doesn't really backspace, but that's the only key that doesn't work 100%. Can anyone hazard a guess as to why that is?

I am looking for feedback anyone has on both ink ribbon supply and platen refurbishing. One of the places quoted me for my Corona 3 ink ribbon at twenty dollars a ribbon and ten dollars shipping/handling per order. I find that incredibly steep when compared to other ribbon suppliers, but he goes on to cite correct thread count, et cetera, on his site. I want to know if it's worth it to buy from Robert Earl De Barth over Vintage Typewriter Shoppe, who carry a six pack of ribbons for forty dollars.

Secondly, I would like to know if anyone has experience with De Barth's platen refurbishing compared to J.J. Short. Both of them are relatively equal in price, but again, Short is a bit less. De Barth seems to have a lot more experience under his belt in regards to that, but then again, my Corona 3 is one of the most common typewriters around, so that extra experience may be superfluous in this case. What about the product itself as supplied by either one? I'm sure their formulas are different to some degree. On that note, is it possible as far as anyone knows to get a natural rubber colour platen? Or does the nature of it make that unreasonable or impossible?