Here's a little tip for using RTV type sealants like Yamabond and '3-Bond' (my favourite). Coat the surfaces (Obviously the mating faces MUST be flat beforehand). Don't put on a sealant thickly, just an even 'smear' should be enough. Screw / bolt up the casing 'snugly' but don't tighten it completely -Just 'tweak it'. Let it 'go off' - overnight, (or for a few hours), then come back later and fully tighten the screws/bolts to final torque. What this does is, it lets the compound solidify conforming to the mating surfaces BEFORE final tightening. Then when you finally tighten the screws, the compound doesn't squeeze out of the joint, because it has solidified, it just compresses, sealing the joint properly. If you just tighten it all up while the compound is 'fresh', it just squeezes the compound out of the joint and later, with temp changes and inherent metal distortion the seal can open up.