How do I repair our Polder thermometer display?

I recall something similar cropping up on the community forum a while back.

You can get anisotropic conductive film tape: 

https://www.3m.co.uk/3M/en_GB/p/d/v000073742/

if you can manage to separate and clean up the existing connection which usually requires a bit of heat eg:

"Bonds made with 3M Anisotropic Condustive Film Adhesive 7303 are repairable
by heating the bond-line to above 100°C (e.g. with a hot plate or rework tool) and
peeling the circuits apart. The bond site then requires cleaning with a solvent, after
which the circuit can be re-bonded using a fresh piece of ACF 7303. Solvents such
as 3M Novec Engineered Fluid HFE-72DA or Acetone may be used."

There was a tutorial showing someone doing this type of repair, which might be worth a search for. 

You probably want to practise a few times on another disposable device first though as it looks a bit tricky.

Adafruit do 'Z axis' anisotropic tape in smaller quantities:

https://www.adafruit.com/product/1656

I also recall there being flexible splices available with the anisotropic tape pre-attached either end, which allow you to re-terminate the ribbon if the end is damaged.    

You can also get T-bar tips for soldering irons that help with such repairs:

https://www.amazon.co.uk/CITALL-Soldering-T-iron-Ribbon-Repair/dp/B07BBMD8DW

in which case a quick reheat followed by some pressure might do the trick, or alternatively help with removal without damage ready for clean-up and new tape.

As you noted, there are videos.  Not all are particularly useful or well-made.  But this one I am going to try as it seems, as its poster alludes at its end, it is worth a try... in my case, yup.  He demos regular "zebra strip" repair at first, then at about the 7 minute mark talks about just what I need to try:

https://www.youtube.com/watch?v=-QZk9WCz-D8&t=3s

Just out of learning experience benefit, if that relatively simple attempt doesn't work, I might get some of your referenced tape and try replacing the old stuff, but the videos about that I've seen look very time-consuming and require delicacy my essential tremor may not facilitate.  Heck, just holding the soldering iron in place for trying the above linked method may be tricky enough for me.

Thanks to all for your valuable input.  That thermometer isn't the only display issue clogging my workbench.  My 2 year-old Ninja coffeemaker has a crystal problem and was a *** to remove from the machine.  I suspect its problem is related to so-called "Zener" diodes on one of its two boards, but the display works on a different principal than zebra or tape;  its integral and pins to solder points directly on the board, eliminating finicky strip or tape connections. Sounds great, except it failed anyway, thus the suspicion is thrown on board components.

But that's another story, one I think I told here last year.

hafcanadian said:

Heck, just holding the soldering iron in place for trying the above linked method may be tricky enough for me.

The T-bar tip mentioned previously might help you out there if you can clamp things into place. 

hafcanadian said:

Heck, just holding the soldering iron in place for trying the above linked method may be tricky enough for me.

The T-bar tip mentioned previously might help you out there if you can clamp things into place.