Hey, that looks like the original bag that came on that vacuum. That's a great find as that model is hard to find and to find it with an original bag, even better. Too bad the spring broke on your 509. I can't help you there but I'd like to know too how to sew in a spring as I hope to make some bags for some of my older Kirby's that don't have original bags. I also have a 508 myself but mine doesn't have the bag like yours and the handle grip is a bicycle handlebar grip. I've never seen one of those used on a Kirby but I guess it serves the purpose. Also, one thing I have noticed, I think the emtor bottom is black plastic but not exactly like the 505. I would have thought it would have been gray to match the rest of the trim but I've seen several 508's now with black emtors. What color is yours?
Chad Cunningham
Post# 58084 , Reply# 3   1/12/2009 at 21:06 (5,554 days old) by marukap(Saint Louis, MO)  
It is just a matter of carefully cutting open the seam that forms the pocket for the spring. You need either a seam ripper and/or a good pair of straight blade manicure scissors.
Once the seam is completely open, remove and discard the broken and probably nasty and rusty old spring and dump out the built up dirt and grit in the pocket.
At this point I often will open the top seam as well (where the slide closer is attached), removing the stiffeners and, again, removing accumulated dirt.
Next, I thoroughly vacuum the bag as clean as possible, then hand wash it in warm water and plain laundry detergent (no bleach - chlorine or oxygen). You will probably want to change the wash water at least once, then rinse in cool water multiple times. DRIP dry at room temperature, then steam iron.
Be sure not to apply the iron directly to the screen printing.
Now, replace the stiffeners at the top of the bag, either machine or hand stitching it closed. Either way, take you time. Use a top quality, cotton wrapped, polyester core, medium weight thread like Coats & Clarks "Dual Duty."
For the bottom of the bag, you can either salvage a spring from another Kirby bag or simply use a Eureka round belt.
Turn the bag inside-out and carefully hand stitch the sleeve around the belt or spring, spreading the bag fabric out flat and even just in the small area where you are working and allowing the fullness to gather around the work area. Use straight pins to hold the seam in place and to get the ball rolling.
Granted, this is not the world's easiest sewing project, but, once you get into it, it makes sense. Use another, intact Kirby bag as a reference. Again, take your time. If you mess it up, just stop, cut out your mistake with the seam ripper or scissors and start over!