Well, I have two things on this one.
First, from what I've heard from several people in the past, Larson's taping was actually the FIRST from that May 19 weekend in '84. They actually taped 7 or 8 that weekend, this was proven during the last episode taped with Wes/Reva/Sandi, which was also the last ep to use the patterns. If you have the original broadcast, you'll actually hear toward the end of THAT exciting game that Peter was exhausted, and he even says in the midst of it all, "It's late in the day."
Getting back to Larson, there was actually ANOTHER glitch in the Press Your Luck game board that caught the attention of my friend Robert Brown last weekend. This second glitch was not around at the time Larson competed, but it WAS around in PYL's infancy.
In this glitch, the actual light itself was messed up. At times, the light would actually switch patterns MIDWAY. In other words, the light could be on the 14th square of Pattern A's sequence, and all of a sudden, jump to the 14th square of Pattern C's sequence, for instance. Visually, it was very obvious, and it took the first 2 tapings for the techinicians to make it stop that.
Now imagine if THAT glitch was still active when Larson competed. You can picture if he was about to stop the board when it was going to hit #4 in current pattern... only to suddenly glitch at that moment to the location in another pattern where a Whammy was lying in wait.
The possibilities are endless, one can only imagine.