Here is the link to the discussion on using Java SW to copy your NVRAM data using the TDS784C internal floppy: https://www.eevblog.com/forum/testgear/tektronix-tds500600700-nvram-floppy-dump-tool/
There is seller on eBay that sells those two chips (or the equivalent thereof) mounted with external coin cell batteries on top of the chip. He has gotten high ratings from other TDS scope owners on their quality. He states that he will program the chips with your backup data if you want. You still need to remove the chips yourself though - so you will need a good quality solder sucker like the Hakko. There are also YouTube videos showing how some pros removed the chips - you should look through them. Some TDS owners have said that just heating the chip pins caused the chips' batteries to drain - some claimed that apparently the chips' batteries were right on the edge.of failing.