I just recently...
got my first Model XXX as well which I picked up fairly inexpensively. Just like yours, sfcoronet, I had to give it a "spa" treatment. Mine blew out a cloud of dust when I first fired it up as well, because the exhaust filter and the dust bag were caked with fine dirt. The cord also had electrical tape on it, and I'm not a fan of "taped" cords.
I bought a new cord from eBay, put in a new filter and dust bag, and replaced the motor (as the bearings/brushes were shot in the original motor). Total cost to restore this baby: $50. Using it to clean my apartment...PRICELESS.
The suction my XXX has is "decent"...good enough to clean bare floors and low-pile carpet and furniture...yet even with a replacement 535 watt motor, it doesn't pull quite as strong as the later models I have, such as the Models L and G. Anyone else notice this between the XXX and later models?
Also, just a side note (and someone please correct me if I'm wrong): cloth dust bags aren't supposed to be laundered because they're treated with a sizing that helps them to trap dirt better. It might be advisable to purchase a replacement bag on eBay...they run between $12 - $20.
Here's a pic of mine:
