Hi Stan,
Please make sure to follow-up the cabling guidelines mentioned here: Cabling
I know above link is for inline adapter but it remains true for gig 1/0 while using WCCP, too..
You may want to try same thing on gig 2/0. If the same issue continues with gig 2/0, it may be the cabling or the interface issue on router / switch where it is connected.
Can you paste the sh int g 1/0 interface output here while it is workign and not working ?
What is the status of interface (on switch / router) connected to WAAS gig 1/0 when it shows down?
If the issue continues, you may want to open up a TAC case as this may be the hardware issue on interface itself.