Yes - the Buster 5731 IC normally runs cold by comparison.
It's not that common for IC faults to cause the symptoms you're describing, but it can happen in rare cases, e.g. broken bond wire termination.
Are all of the IC sockets on the board brand new? That would be my first suspicion. All of the IC leads should be carefully cleaned as it's common for dirt/oxides to cause intermittent contact issues in the sockets. Clean the leads using a fibreglass brush then isopropyl alcohol.
I can't comment on the solder joints without seeing it. Though it'll be a plated through hole board, which is by far the easiest to hand solder correctly.