If it is the original edition then that is an old amp! I own the 3040 of the same vintage and use it in my garage to power outdoor speakers. Mine has never needed repair in the 35 years I have owned it and it survives 90+ degree heat in the summer and freezing temperatures in the winter. I try and turn it on/off when using/not using it but sometimes leave it on for a couple of days unintentionally.
I can provide two observations, first, my amp has handled many, many on/off cycles without fail and, second, a 35-year old amp can fail at any time. One last thing, because it does get slightly warm and because it is so old, I would probably opt for turning on/off.
I can provide two observations, first, my amp has handled many, many on/off cycles without fail and, second, a 35-year old amp can fail at any time. One last thing, because it does get slightly warm and because it is so old, I would probably opt for turning on/off.