Speed control knob has come off

Question edited for clarity, full 'make model (what it is)'.

Videos and where to buy.

https://www.google.com/search?q=m51+pronto%2C+replace+carbon+brushes

Service manual

Pronto Series M50 M51 M61 - PDF Free Download

http://docplayer.net > 58262751-Pronto-series-m50-m5...
Refer to Motor Testing on page 31 or Replacing Motor Brushes on page 116. Replace controller or send to Invacare for repair. Refer to Replacing the ...

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Check the main clutch/brake lever is engaged.

It means the battery voltage has dropped below the operating range of the chair electronics. Either need new batteries or maybe a charger and new batteries. There is always a chance of loose battery harness connections.

It seems to be a known issue. Is it the black disc by the axle in this image?
https://www.monsterscooterparts.com/brands/invacare/models/pronto-m51/motor-and-gearbox-for-the-invacare-pronto-m51-and-pronto-m61-power-chairs.html

I would put a large hose clip around it. If you have the old one, you can probably get a replacement from Home Depot, or contact the company for a free one.

http://www.invacare.com/cgi-bin/imhqprd/contact.jsp

More info and manuals etc

https://www.google.com/search?q=Invacare+Pronto+M51+gearbox+grease+oil+plug

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1. Pronto M51 Troubleshooting‎

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Service Indicator Light Diagnostics - Invacare Pronto M51 ...

www.manualslib.com > ... > Pronto M51 > Maintenance manual

Invacare Pronto M51 Base Manual Online: Service Indicator Light Diagnostics. ... Invacare power wheelchair owner's operator and maintenance manual.

You will need to contact a service tech in your area to do this. They should have a special programmer box that can adjust the settings on the chair to improve the chairs performance.

I suggest you visit http://www.invacare.com/doc_files/1125085.pdf for further information.
Best of luck! Handicap Wheelchair Vans Hand Control For Cars Mobility Scooter Better...

Have you had the batteries load tested? How do you know the batteries are good?

Check that the speed control on your joystick is set to high. If it is then you probably have a battery problem. Even with all the lights lit on the joystick you can have one battery of the two on the chair that is not charging fully. This will cause the M51 to creep and not work correctly

Hi. We can supply, but try your local Invacare dealer. If you have luck, send us an email,
[email protected]