My 40d' top dial is not catching the gears

Same problem here. The rubber must be expanding itself somehow.

same problem with my old 50D, I gave it to my friend, I will give him this link, hopefully he can fix it.

thank you for the information

Martin

Glad to see this thread has helped a lot of people

For those with wobbly hands and poor eye sight, I got an old android phone and dslr controller and use that to change settings in my 40D with same issue. My reciever remote busted so found another android phone and downloaded control software. Old phones are still useful.

This just happened on my Canon 40D. I followed your instruction and it worked. Thank you.

At first, I didn't understand how to access the wheel without taking the camera apart. Others may have the question too so I have a picture showing how the paperclip is positioned to gently pull the plastic wheel away from the dial. It is a little tricky to work the paperclip under the dial.

For extra holding power, I glued the top and the bottom of the dial. I marked the 1st glued section with fingernail polish. There were 12 total clicks so I moved the dial 6 clicks to glue the opposite side of the dial.

^nicely done - and welcome to the forums!