The push button units are known to produce odd symptoms, a cold solder will give you all sorts of strangeness. If you decide to check there, you're going to have to remove it to inspect.
If, however, you have the dreaded servo unit, (vertical push button unit) all bets are off.
The 82's, I believe, have the horizontal push button unit, that is the one I referred to at first.

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83 SD

84 CD