PS4 controller is knackered on the R2 button.
Took it apart and give it a quick wipe with alcohol. Nuffin.

Took it apart again and replaced the pads for R1 and R2. Nuffin.
Took it apart yet again. Removed the circuit membrane, cleaned with soapy water, rinsed, cleaned with alcohol, used the L1 and L2 pads on R1 and R2. Nuffin.

Looks like I'm buying a replacement circuit membrane. At least I had the chance to remove those stupid shock motors.