New 1130 Massey owner here! :)

Under the cover as indicated by the arrow are some bolts that retain the torsion plate which controls the draft sensing mechanism for the 3 point linkage. The 1100 we had used to have a nasty habit of breaking these off. It is a very good idea if you are using the tractor for a lot of 3 point work to remove that tin cover occasionally and check the tightness of the bolts.

Related to the above: Behind the white arrow is a small clevis pin retained by an R clip. This can be removed and replaced in one of ( 3? ) alternative holes to increase or decrease draft sensitivity. If you are using an aggresive implement like a chisel plow, you might find the whole draft control mechanism "chatters". Moving that clevis pin into a different hole position ( I can't really remember if its upper or lower! ) cures this. One last thing, and its important. For safety's sake Make sure that the 3 point is in POSITION control not DRAFT when attaching or a removing an implement.