omnitravis

So I have an older German 12 round magazine, it is in pretty bad shape, but the the only thing I should need to replace instead of just give a rough cleaning is the tube, and maybe the spring. I think the spring is okay though. I hate to say it, but it was stored very poorly, saying it has seen better days is kind of an understatement. There is basically a hole of rust in the top front end

I found some parts online at Sig Sauer Accessories
but they dont have tubes, or complete kits, which is another option. Anyone know a website they can link me to with the tube or a parts kit?