I recently broke the handle on my  Rigol Dm3058E multi meter. The handle itself is actually fine but there are 2 keys on each side of the handle that go inside set holes on the equipment to lock it in a certain position. To fix the problem I designed a set of inserts that have the broken keys. I works really well on my equipment and fixed the problem.

I suggest printing the inserts in PLA with 30% infill. Also add a modifier to the base of the key with 100% infill for extra rigidity. I have attached a screenshot from my slicer to show what I mean.

Before pushing the inserts make sure to break off the exiting keys inside the handle and properly file it off or melt it with the tip of your soldering iron. There is no need to cut it the exiting keys all the way to the bottom as the insert is only 8mm thick.

Best of luck fixing your Rigol handle