On tbe gearbox appears a stud, which is one of two points that secures the foremost part of tbe chainguard.  This stud is front bottom.  On loosening the nut on this stud, it began to bind and caused the stud to screw out with it.  A closer look revealed, that gearbox oil was also leaking from that point.  Is this normal ?  When I screwed the stud back in, it seated, the nut loosened and was again, able to secure the guard.  

As per the manual pictures, leaking from this point isn't normal as it should be a blind hole......however I have the same problem and found on two gearbox cases that the tapped hole goes straight through into the gearbox. Might be a fault of re-tapping or previous repair. I solved the problem with a new stud and some locktite.

I have accessed the stud.  There appears to be good thread purchase left in the gearbox case.  It does appear however, that the chain guard has loosened previously and burred the tbread.  I have removed the stud and run a 1/4 inch 24 tpi die over it, thus recutting the damaged thread.  Does the stud, when screwed into the gearcase bottom out in a blind hole ?  I screw the stud into the case thread and it enters approx. 9/16” to 5/8” before it bottoms out.  Is this normal ?