Guys, I can't account for this, but when I opened the project today, quick swipe worked as it ought to. I am aware of nothing I did differently. I didn't even restart the computer or relaunch Logic between last night and this morning.
Thanks everyone for your help, and David, one last question, if I may. I did take your suggestion and import the track with the difficult take folder to a new project using the File browser. Quick Swipe did work in that new project (I had not yet discovered that it was also now working in the original project). My question is this: in the new project, the imported material opened at odd lengths. The take folder was shortened, but when I disclosed the individual takes, they appeared at their original lengths, extending beyond the now shortened upper region of the take folder. I went back to the original project to check if I'd performed any unexpected edits on the taker folder which might have accounted for this, but saw nothing unusual. Can you explain?
Thanks again. And I'll be glad to end this thread now. I have to figure either I did something bone-headed with the Quick Swipe, or else the project was corrupted and somehow reconstituted itself.
Logic Pro 9.1.7 32 bit, OS 10.6.8, iMac, 3.2GHz-4 GB RAM, MOTU 828 mk3 Hybrid