Tried removing the 5 mm hex bolts under the plastic cap on the handlebars of a 2017 GL1800 near the clutch reservoir to install a phone holder. Bottom bolt came off after overcoming reasonable factory tightening with normal results. Upper is a PITA. Tried multiple 5 mm hex wrenches to ensure I wasn't rounding them off. Drove the hex in with a hammer when it started to round off, then a baby sledge to regain a bite with the hex wrench. Tried an impact driver with a phillips bit. Let WD-40 soak in. The hole is rounded now. Wasted money on a titanium speedout screw extractor set. The drill part was non-effective so the gripping reverse threaded end couldn't get a grip. Considering cutting a slot with a fein multitool or grinding a slot with a dremel tool. Haven't tried heat yet. Any other ideas besides parting out (grin)?