Spice Low Power

[BobVA]

I just got a 34C as a possible LP conversion candidate. Battery contacts and ribbon cable were eaten away, but I spliced some wire-wrap wire to the last good bit of the ribbon, cleaned the power switch and was happy to see the calculator worked. For a day.

It then developed erratic operation, which seemed vary with pressure on the case, so I disassembled the "sandwich" (what a ghastly bit of engineering that is!), cleaned all the chips/contacts and reassembled it, but it didn't work any better and continued to degrade. Now it just lights a couple of segments.

I'm not sure if I damaged something, or if my tinkering was unrelated and perhaps it's a slowly failing power supply component that's the issue, but I was planning to convert it to an LP anyway, so...to my question: While I had it apart I noticed distinct impressions (grooves) in the printed circuit board under the IC legs, particularly under the leads of the large IC.

Is this normal? Or does it indicate that perhaps the printed circuit board is damaged (hence not being a good candidate for repair with the LP circuit)?