HP Scanjet 5300c scanning trash

[indnajns]

For as long as I've had this scanner it does this. It randomly will start scanning orange "trash" lines. Resolution doesn't matter. Not related to "jostling". Scan, scan, scan, then the next scan will have orange lines. You may get 100 scans, you may get 10, before the lines start. Of course, HP's tech support is clueless. They suggested I didn't need to scan at 1200dpi. (then why'd I buy a scanner that could??) But it's not related to resolution, anyways. Same pict scanned several times will show different trash lines. Just as randomly, the orange will go away. I've tried flipping the lock/unlock switch. (sometimes that seems to work, but I think it's more coincidence than anything) I've tried unplugging. I've tried on/off, stop/restart. I've even tried turning it upside down and shaking it like an Etch-a-Sketch. That almost helps. At least, the trash gets lighter.
Anybody else seen this? Is it unique to HPs? And how do I get rid of it?