I just had to repair one of these springs on another vehicle I had the upholstery shop, an OT brand but the spring and location is the same. It wasn't broken "yet" but had rotted through to the point it was going to; it was effectively broken at that point and wouldn't take a bend - not unlike welding the spring steel together: It's joined but the steel won't do it's job right there. We didn't have another spring on hand to replace it with and really the spring was good except for that one point (the foam had been all chewed up by a rodent right at that point), so I decided to deal with it rather than waiting on a new spring.
I forgot to take a picture (kind of hard to describe and now it's been recovered) but I made a support plate (about 4" long) from flat stock with tube steel I cut down the middle and tacked onto the plate to support the spring and spread the load out across the spring to good springy steel. I had a couple of those 1/2 tubes tacked strategically to secure the spring from moving forward/backward. Underneath I added a stout V-spring I got from the upholstery shop, also secured with those 1/2-tubes tacked onto the frame. Located the spring in the center so the plate wouldn't (hopefully) create a stress point.
I rounded off the edges of all steel where anything was contacting the spring.
Didn't take long once I decided how to approach it. Maybe 1/2 hour of welding and cutting and then painted everything. Will it hold up? Time will tell but no reason it won't.
