Stick Dpad on the purple saturn-style ps2 pad, what to do?

I got a purple colored saturn pad for ps2.
I didnt use it much, just very slight usage for a few months.
But now I found that the dpad is kind of sticky.
It is really hard to perform combo like 2626 (dfdf), however, 2424(dbdb) and 623 is fine.
what is the problem? is there a way to fix it?

just unscrew all the screws on the back and take it apart and go over the sticky parts with a cloth soaked in warm soapy water, its easy to put back together

you sure you didnt spill anything in it?