I used the long-handled bypass lopper to harvest the 3D printed soaker hose splices and clamps, which made the sad state of the lopper’s bumper painfully obvious:
Contrary to what you might think, those rivets never had a head on this side and the bumper seems to be held in place by an interference fit with the plastic handle cover.
A bit of cutoff wheel work removed the crimped end on the 5 mm stud holding the bumper to the pot-metal dingus:
Whacking it with a punch separated all the parts:
The gray thing is a silicone rubber vibration isolator that’s a bit too large in all dimensions, but surely Close Enough™ for present purposes.
A length of 5 mm shaft became the new stud, with M3×0.5 threads tapped into both ends and a pair of random screws held in place with red Loctite:
There are no pix of the drilling and threading, as it was accomplished after a shiny-new 2.7 mm “titanium” metric drill from a not-dirt-cheap set shattered in the shaft:
The blue color on the flutes is Sharpie to remind me it’s defunct. I completed the mission using a #36 drill with no further excitement.
The dingus is now held to the lopper with JB Weld and, should that fail, I’ll drill-n-tap the rivets and be done with it.
The Smell of Molten Projects in the Morning 
If JB Weld fails, back away slowly and treat whatever responsible hellspawn politely.
It is completely devoid of a maker’s mark, suggesting it arose from primordial ooze by sheer force of will; it may regard me as nutritious.