Glad to see this post, reminding me mainly to power up my 575 for a few hours. I have a plastic tube of radioshack silver solder that should outlast me. From what I remember from Tektronix, minor lead soldering was OK on a terminal. The worst is the joint could lift from the strip, it won't cause the entire scope to fall into the ocean. Wrap a wire around all the leads in the joint if you are worried.
Post any updates on your unit, glad it wasn't scrapped for guitar amp tubes.