Drive Belt/Power Steering problem

[arch0035]

I tend to DIY, especially when it comes to minor maintenance stuff. So I decided to tackle the project of replacing a worn out drive belt in my '99 Corolla. Took me all of about 15 minutes once I downloaded this configuration map
http://ytosa.home.att.net/1ZZ-FEengine.jpg

Well, the next day the car started making a grinding noise when hard turning, especially slow turning like into a parking space. As you may have guessed, the power steering pump was not functioning properly. So much for the nice and easy DIY!

The power steering pulley seems to be the issue. When I took the new belt off, the pulley that drives the PS pump has a great deal of wobble to it. I know this wobble was not there when I installed the new belt. The pulley seems to have come loose, but I can't figure out how to tighten it back down. The bolt just spins when I turn it.

Can anyone tell me how the pulley is supposed to be tightened. Do I need a special tool for this? Or was the new belt too much for the 10-year old pulley assembly and now the threads are stripped?

Any chance I can fix this without replacing the pump?

On a side note, what mayhem will happen if the pulley comes off all together. I put it back together tonight to make a run to the store and by the time I got home, I swear the pulley had even more wobble to it than before. And the belt had started slipping off of the PS pulley.