Kirby Ultimate G wheels lock up when in drive...

Check the back side at the bottom to see if there is a lever (switch) that has an N on one side and D on the other. You press N to roll the vacuum when it is NOT ON. N is for nuetral. You press D when the vacuum is ON and you are using it. D is for drive.

Generation 5, 1996-99
Generation 6, 1999-01
Ultimate G , 2002-05
Ultimate G Diamond , 2005-06
Sentria, 2006 to present

1935 KIRBY Model R*
19?? KIRBY Model 2R
19?? KIRBY Model 3R
19?? KIRBY Model 4R
19?? KIRBY Model C
1939 KIRBY Model 2C
19?? KIRBY Model 3C
19?? KIRBY Model 4C
Model 505 - 1945
Model 508 - 1948
Model 509 - 1949
Model 510 - 1950
Model 511 - 1951
Model 512 - 1952
Model 513 - 1953
Model 514 - 1954
Model 515 - 1955
Model 516 - 1956
Model 517 - 1957
Model 518 - 1958
Model 519 – 1959
Model 560 - 1960
Model 561 - 1961
Model 562 - 1962
1963/64 Sanitronic VII (Sirocco)
1965-67 Dual Sanitronic 50 (Sirocco)
1967-70 Dual Sanitronic 80 (Avocado green)
1967-70 Dual Sanitronic 80 (Avocado green)
1970-73 Classic 1CR (Medium brown, gold bag)
1973-76 Classic Omega 1CB (Dark brown, dark brown pinstriped bag)
1976-79 Classic III 2CB (Candy-apple red, plaid bag)
1979-81 Tradition (Dark blue; intro of paper bag)
1981-84 Heritage (Gray/orange)
1984-89 Heritage II Legend (Charcoal/gray/red)
1989-90 Legend II (Dark rose-pink)
1990-93 Generation 3 (Alabaster)
1993-96 Generation 4 (Medium gray)
1996-99 Generation 5 (Maroon)
1999-01 Generation 6 (Black/Yellow)
2002-05 Kirby Ultimate G
2005-06 Kirby Ultimate G Diamond

http://www.vacuumwizard.com/history-of-kirby-vacuum-cleaners.html

The years each were made/sold are as follows:
Generation 3, 1990-93
Generation 4, 1993-96
Generation 5, 1996-99
Generation 6, 1999-01
Ultimate G , 2002-05
Ultimate G Diamond , 2005-06
Sentria, 2006 to present

remove the brush roll clean the brush end bushings and replace with a new belt

When wheels lock when vacuum is OFF - it is normal. If it happens when Kirby is ON then there are a few things that may have gone wrong

Primary drive belt is broken or something is wrong with plastic gears. See how to check the primary drive belt HERE.

If it is fine and gears are spinning - then something must be wrong inside the transmission. Parts for tech drive are not available from manufacturer so you are on your own. It is not really complicated - 2 clutches that engage and disengage depending which direction you push the vacuum. But if something in there is broken - you have to get a new tranny. It is not like getting a transmission for a truck but it still will set you back by about 100 $.

Good Luck
Rocky

Try my troubleshooting guide. It may answer at least some of your questions....

http://reviews.ebay.com/COMMON-PROBLEMS-WITH-THE-KIRBY-VACUUM-TROUBLESHOOTING_W0QQugidZ10000000003800312

Marci

do u put it on drive or neutral? does the wheels spin when on drive? is the height adjuster on the right level?

Hi, I'm Jon IO used to sell these machines and I also own an Ultimate G, And sounds like to me it's a loose or broken transmission belt, I think you should have your local Kirby dealer take a look at it or even a good quality vacuum shop will be able to look at it.

No, you just need to take it to a shop for repair.