They were going to build up the shaft with hard weld and machine/true to fit bearing. Thoughts were that the welding process would weaken the adhesive, but this side should not have the torque applied that the drive side would have. This side is more of a "follower". I understand that this may not work, but I could not find any information saying that this had been tried before and did not work.
I am skeptical of buying a used shaft on ebay. I hear of ebay junk all the time.
If the welding doesn't work I will most likely order a new shaft, maybe 1 for an Assault to rid this sled of this drive shaft issue.
Do you have any pictures of some that you have done while installing the splined hub process?
The plain hub is cast aluminum! There is no Aluminum "hard weld". Which indicates to me even the "Machine Shop" is in over it's head. The more information you provide the more I realize there are people out there that have zero knowledge base in a profession that demands a very broad knowledge base.
Here is a pic from my SW album of my double splined drive shafts;
The complete drive shaft with 58 Tooth C3 sprocket, Wahl Brothers Billet aluminum flangettes, standard bearings for prototyping (will get Ceramic Hybrid bearings when time for final installation), Happy Face Collar with fasteners upgraded to Titanium, 9 Tooth 2.86" Pitch involute drivers (custom made by C3 for me), Yeti Disk with my hub, my large flange flangette holder which also doubles as the brake mount, the Wilwood caliper has been upgraded to Titanium bolts and Titanium brake pad pin, Titanium mount bolts as well as Titanium shaft bolts; 5217 Grams
There is some trimming / profiling to do on the brake mount, this is the first one just to visually check all clearances and dimensions in 3D, to verify I was not overlooking anything in the CAD process.
While this is economical for me and my personal use. It would be cost prohibitive for me to make and sell these. As it takes two shafts to make one of these, even if the parts were free. Once you add in the Labor time for disassembly, cleaning, assembly, truing, and gluing; even a new shaft is cheaper.
When the machine shop fails to deliver a functional fix, PM me as I may have one in my pile of take offs that has a good plain end bearing fit.