sometimes if you get spool that is tool “long” that the muffler slip-on can knock it off as the rear suspension articulates up and down. I’ve seen that happen before.
Since it’s for service purposes I would suggest finding someone that’s qualified with welding on aluminum to weld one back on if you really feel you need it. Wouldn’t be too hard to fabricate a threaded tab which is basically what that is and then weld it on. The welding of aluminum can be difficult and I would not let someone do it it’s not a certified welder because it could really damage your swing arm. Sorry man that sucks, but I hope this helps.
my old pitbull stand had lift arms that could slide in and grab underneath the swing arm and didn’t require the spool. might consider going that route too.