Fixing Asteroids explosions

Pretty much every Asteroids I've ever played has had an intermittent issue where explosions sometimes display as a flat, inconsistently dashed line instead of the animated dots. They can be either horizontal or vertical, it can happen one in five or ten or fifteen explosions. Everything else works fine. I have heard that this is caused by bad LS161 counters.

I'm wondering if this is usually the case, and if so, whether there are any good techniques to isolate the faulty ICs. There are a ton of these on the PCB and I don't want to socket everything to track down a single faulty IC. I don't have an IC tester, scope, or any advanced diagnostic tools, just a logic probe. The problem is so intermittent and only occurs during gameplay, so it seems like the probe isn't going to be much help in this case.

I read on the (sadly now defunct) usbdesigntech.com site that the following 161s were very prone to failure:

Type SA 74LS161 with a date code of 8108
Type SA 74LS161 with a date code of 8045
Type SA 74LS161 with a date code of 8046

I could start by swapping any of those I find, but I was curious to know if there is a better way to do this.
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Received on Sun Feb 3 13:48:31 2013