Help needed identifying missing part. Atco 14 inch cylinder mower

I am hoping someone may be able to identify what part is missing from this mower, and / or confirm what manual matches this machine. 
There is a plate that attaches to the rear of the engine, just below the exhaust onto the main engine body. This has come loose and and assuming some attachment mechanism for it is missing. I am also unsure what the small hole on the engine block is. This was a great little mower when last used by me ( probably 15 years ago) and would like to fix it if possible. Any advice will be gratefully received. Please see attached photos. The reference number on the side says 6241 R if this helps.