Well I'm in the same place. M 3T has a leak somewhere and I cannot find it. I smell the anti-freeze and find some dried coolant on the water pump, front and side of engine and front of oil bag but everything is dry around the pump and both hoses. I cleaned it all off at the Indian dealership about 10 miles from my home and when I returned there was no sign of a leak.
This all started after I had the coolant replaced at the dealership about 500 miles ago. I have a Samco hose and clamp kit so will tackle the job with a friend over the next week of rainy days. I read the procedure in the shop manual and it mentions a 10mm bolt in the head to remove when refilling the radiator. I believe 1olbull told me it was on the left side but the manual doesn't locate it.
On the stuck allen head, I had a couple of those on my 07. We call it "nature bonded" in the maritime world. One of the problems is that the bolts seem to be of soft metal. I found the opposite on my 3T, they were all barely tight, with some loose and with two having fallen out.
On the mesh radiator, I would absolutely retain it. Roll Bar and Frame paint comes in a semi-gloss and should work fine to paint the mesh. It's sold at NAPA dealers.
Edit: And one more. I agree on the PB Blaster. We use it on nature bonded outboard motor nuts and bolts. Good stuff.