March 24, 2022 at 7:11 pm
#1718
The symptoms do indeed sound like a contact foil fault. However, the non working buttons share two of the same foil/PCB contact points (R1, R4 in the manual) so perhaps the connection between the keypad foil and PCB is dirty, or misaligned. Try removing the clip, cleaning and re-assembly.
Otherwise sometime the PCBs do sometimes go wrong; I have had a couple ☹