DO not put in a larger fuse, the wiring is not capable of more current.
Can you explain the differences in connection between the two switches. Does the PIAA have a LED light? Then again, a LED draws such little power it should not matter.
Possibly, the factory switch is bad.
Hard to say without knowing exactly how you wired the system.
If you can, make up a hand wiring diagram of what you did, and scan it and send it to me at
f5fstop@comcast.net. I would be curious.