Got a loose screw? VIBRA-TITE

We've loved our New Holland TC29DA compact tractor since we got it back in 2005, it's been a real workhorse for moving dirt, rocks, snow, gravel, trees, etc...  But it's had one nagging problem since about 2010...  The transmission case bolts that separate the HST from the clutch casing habitually get loose and back out.    The tell-tale sign is that it starts leaking hydro fluid while parked, and when under heavy hydro load, will actually spray out from the loose case seal.

The dealer says he's only seen it on tractors that use a 3-point hitch backhoe, but our backhoe attachment is the New Holland brand that utilizes a subframe to transfer some of the force up to the front frame under the loader.

So far we've tried;
 - re-torquing the bolts (#21 in picture, but installed from the front)
 - removing all accessible bolts, cleaning the holes and bolts with brake cleaner/degreaser
 - applying medium-strength blue thread locker to all the bolts
 - buying new case bolts with new captive lock washers and replacing

All have failed and come loose again in between 10-50 hours of use.

This time we went for the proverbial belt and suspenders approach.  I replaced the M10x30 bolts with grade 8.8, each have a polyester spray locking patch.  They've also been coated with VC-3 grade Vibra-tite, a non-curing acrylic gel (dissolved in MEK) that prevents any vibration loosing as the material stays in a soft and cold-flow state.  The bolts are then kept under tension with Belleville cupped spring washers, that apply about 550lbs of work load when flattened.

Original bolt on left, replacement on right

Get ready to work a bit putting the new ones in, they have to be cranked all the way in as the VC-3 cold flows under work load, but it does feel secure.  I'm feeling pretty confident that'll hold it in as I watch the snow pile up once again outside the window...