HP-34C display malfunction, need help


I have an HP-34C, and rebuilt it yesterday to make sure
that there are not loose inner contacts (this is the unsoldered spice series).

Example, if you type in Sin(45) .
You can see it calculating for a few seconds while
it calculates. the result is correct.
It even passes its self test 8,8,8,8,8,8,8,8,8

Let's say you just start entering a number:
Each time you type that "2", the whole display
blinks in an unpleasant way.
The "-" and all the commas light up.

Reminds me of things that maybe an HP-25C
might do, they would show comma activity, if I recall.
Luiz states that many of the SPICE series do what I am saying, but his sample of the 34C does not, and I never saw any HP-34C specimen do that before.

So three questions:

Did anybody see early versions of the 34C actually do this by design ?
Did anybody see a unit degrade into this condition ?

Did anybody figure out a way to fix it, for example,
whether the big chip, or the power supply is to blame ?

If U tell me what the problem is, of course, I will fix it. Cosmetically, the unit is clean as new and worth trying to save.

- Norm

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