Sam,
<span style="font-family: helvetica;">Your Kirby 510 was a great find--congrats! Being in Rochester, MN it may be that the sweeper belonged to a doctor's household and got excellent care.</span>
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<span style="font-family: helvetica;">I'm in Mankato/North Mankato and just saw a Kirby floor polisher--in the original box--at a thrift store here. Don't remember the price--although it likely wasn't that much. Judging by the dial and matching Kirby logo, it's at least from the same era if not the same year. I'm not an expert, but it seems to be in decent shape. Let me know soon if you want me to purchase it for you; There may be other collectors around the area as another local thrift store had a Kirby Classic that didn't last long on the floor. </span>
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<span style="font-family: helvetica;">Paul</span>