My grandpa has an old 2mh in the grove. He quit picking ear corn in 1973. He kept the elevator in the shed until about 13 years ago. He said he did some work to it not long before he quit picking. I will ask if he wants to get rid of the elevator if you are interested. If you need any other parts he has the rest of it too.
I don't know much about red pickers, but most companies seemed to use common sizes of drag chain for those applications. Check out the website farmchains.com--they have a nice selection of flat links, paddle links, roller chain, and other stuff. (I have no connection to the company.) Some specialty stuff, like the old "tooth" links for some sizes of gathering chain, are NLA, but it's a good option if you cannot find a parts machine.
I have bought chain and parts from Farmchains also. They also have some of the specialty links available which are not shown on the website. They got me gathering chain links for a New Idea picker last year. I emailed then a picture and the no. of the link and they had them. Good people to deal with.