The Getaway with Rottendog Power Driver board issue

[PinPal]

Hi Folks,
I have a spare Rottendog Power DA-12697 -1,,  pictured,  this I use while the other board is away for repair.
Installed The Rottendog in the Getaway, played it for about half hour with no problems, then I lost some of the switches where the game went into ball search mode.
Fuse 104 - 3,amp blew and then I found the heat sink with the red circle was extremally hot.   Forgive my ignorance but what does this doo ?
Replaced the 3 amp fuse, powered the game back on, all good.
Had this Rottendog in my Party Zone for a long time with no issues.
Just wanted to no if its normal for that heatsink to get very hot, I didn't want to keep playing the game incase it was doing damage to the game.

Original Power Driver board has an issue where it will crash for no particular reason, strange thing is if I am playing it and its under load like multi ball all flippers going it wont crash, but out of the blue it will. Will be sending it away for repair.
Hope you can help
Many thanks

Pinpal....