Amiga with broken chip

When trying out my new Gotek drive, My Amiga did her own thing.
When the Selector.ADF was loaded, the selection bar keep on scrolling down.
Checking the joystick circuit, I noticed another resistance between pin2 of joystick port 2 than the other pins.
First I checked the Resistor pack RP401 but it seems ok.
Then I replaced U15, a 74LS157 (multiplexer) this fixed the problem.

My Amiga is now running again.