I pushed the on button and kirby g5 starts but when releasing button motor stops

power switch damaged contact your local kirby agent for repair

This machine weighs in at a hefty 25 pounds. The self propel feature, however, makes pushing it almost effortless.

First, twist the belt lifter dial on the front of your kirby roller brush head counter clockwise to take the belt off the motor fan pulley, then undo the latch at the top of the head to release it from the vacuum body, then take your hose and mount it to the place where the head was hooked onto then lock it down with the latch at the top of the hose. That should get you going.

No reset button. It sounds like you might have one of several possible problems. Some ideas I have that you could try yourself would be to check the lockout switches: there is one behind the head nozzle, maybe the nozzle is on crooked, if so, maybe not engaging the safety switch, the other lock-out is located where the bag screws on, unlock the bag and re lock it to ensure proper fit. Otherwise, take it to the shop because it could be the motor, the cord, the switch. Hope this helped ya. Let me know. Thanks, Rene (the Vacuum Doctor)

No luck on finding the G5 manual but Kirby as released a standard manual that works for all Kirby models

http://www.goodvac.com/articles.asp?id=135

I would say that it is a short in the power cord.

Try my troubleshooting guide. It helps with do-it-yourself Kirby repairs. You'll also find links to directions, parts (cords too!!) and free repair guides!

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

check the cord. see if there are any frays. or broken spots. usually it is one of 3 things. 1, faulty electric cord. 2. the attachment or floor nozzle not being properly attached( kind of a duh issue LOL)
3. a faulty switch assy. the switch can be kind of a bear to replace. I hope it is the cord. if not i would take it to a kirby repair person, because it is very easy to damage the motor assy when replacing a kirby switch. trust me i have damaged a few learning how to do it

The carbon brushes in the motor need to be replaced. Very IMPORTANT....... DO NOT run the Kirby anymore until you get this fixed. If you do, the armature will be in danger of being damaged. (and that part is expensive!) The carbon brushes are reasonably priced, and you can use this online guide to get to them and change them. It's a guide for replacing the power switch, but it will help you change the carbon brushes too. Hope I've helped...
Marci

http://reviews.ebay.com/REPLACING-THE-POWER-SWITCH-ON-ANY-KIRBY-G-SERIES-VACUUM_W0QQugidZ10000000003752018

nuetral/drive, the g series has a power drive motor for the back wheels