L297/L298 board concern

Guys,

I have a L297/L298 board that seems to be getting REAL hot. It's
basically just the circuit from the L297 datasheet. A friend of mine
had the board made up with another order. I built it a few months
ago, got a motor spinning (I think I was only using about 12v supply
then), then put in on the shelf. I was playing with it today.

When I run it, the L298 gets really hot. In fact, I didn't have a
heatsink on it and the smoke got let out. After replacing the L298
(and adding a heatsink), it seems to work OK, but still gets very
hot. I don't want to run it too much for fear more smoke may ruin my
day.

I am using a 24V power supply, the motor is a size 23 that is rated
for 3A, but should work fine with 2. It is stone cold when running
at low speed from the driver. The L298 on the other hand could cook
dinner.

Anybody else have this problem? I'm not sure if there's something
else screwy with the board, but the amount of heat I'm getting makes
me wonder.

Thanks in advance

Gary