Hi Kerly,
16th of September 1980 is the date of manufacture of the engine, add another 5 months (due to Xmas break) and you'd be pretty well around the mark of the mowers birthdate (Feb 1981). There is no way of dating it exactly, but there are various items which give us more of an idea. Now looking inside the drive train area we can see that it was originally painted in "Apple Green" which I already knew because of the throttle assembly and the style of SB stickers that are on it.
Now as far as cutting it higher and butchering the mower in the process, this is absurd. My father in law had buffalo as did many people that planted there lawns in the 1930's onwards. Buffalo is nothing new and he cut his massively large lawn with a Model 45 for 25 years or even more I think.
One thing that will have to be evaluated is the PTO shaft on the engine after you remove that butchered clutch half which will require replacing as a high priority. Leaving it like it is will only inflict more damage if it hasn't already done so to the chassis rails due to running unbalanced and inducing stress fractures.
As far as tapping the adjuster set screws is concerned, that's a no no. If you undo the the two bearing carrier bolts very lightly, you'll find you won't have to use a hammer at all. Honestly it's a tool that's rarely used in my repertoire of engineering. The locking nuts only have to be undone a tiny tad so as to reduce the play that you'll induce into the process. All you need to do is adjust it correctly then do up the two carrier nuts nice and tightly, then check the reel to bed knife contact and if satisfactory then just nip up the lock nuts on the set screws and you're done.
Cheers,
BB.
All I will say is your lawn is way too thatchy and needs to be cut right back to a base level and allow it to re-grow. Then set the height you desire and you'll be right. There's no need to modify the mower in any way, just the actual lawn.
