No sucha-thang on mine either. Just a PTO warning lamp on the “EasyChecker”.
I have that as well, and the 'Whistle too.
On page 43 of the owners manuals for both my cab and open station M9's it says:
Note:
There is a PTO-1 (540 rpm) indicated mark on the tachometer board (gotta love the Japanese terms...lol)
Tractor engine will not start if the PTO clutch control lever is the engaged 'On' position.
If the PTO system is engaged and you stand up from the seat, the warning buzzer will 'whistle' for about 10 seconds after standing up.
This is because the tractor is equipped with an operator presence control
How it reads in both manuals and in the WSM as well.
Maybe not on yours George but in Bulldog's it should work as he has an M identical to mine.
In reality, I kind of wish it didn't. I find it irritating at times.