09-01-2020 10:15 PM - edited 09-01-2020 10:16 PM
I replaced the zoom rocker switch (IMO the only permant fix) on my G30 that had the same zooming out issue, and I filmed a how to video. hope it helps!
04-20-2021 03:25 PM - edited 04-27-2021 01:54 AM
I have the same issue. I bought this Canon Vixia HF G40 in 2016 (it's 2021 today) and this issue has been rearing its ugly head - intermittently during the last six months. Usually, it seems anyway, I experience zooming out only when I've zoomed in 100% (or close to 100%). In my case the zoom slowly creeps back out then stops - without fully zooming out. At first I thought this was some feature engaged or setting that caused the unwanted zooming. Sadly, after reading the numerous posts here - it seems that my wonderful Canon G40 is actually broken - and not supported. =(
04-20-2021 04:51 PM
There is no way to fix this problem other than to send it to Canon. I have had to send my G30 and G40 in a total of 3 times to have that zoom problem fixed. the last time it cost $400.
04-20-2021 05:25 PM
@filbreen - It seems that I've been fairly lucky being that I've gone a solid four years without these zooming issues. But, still, a camera that costs over $1000 should be more robust. As for fixes - I have had a look at @davedogcaddy 's video and it seems that I could buy the part assembly from Canon for roughly $80 ~ $90 and perform the repair myself or hire someone to impliment the fix. At least this can be done - otherwise I'd be looking at buying a new camcorder.
04-27-2021 12:50 PM
I've ordered the part assembly for my VIXIA HF G40 in my attempt to repair the zoom problem. The assembly itself is the entire left side of the camera casing, according to Cannon. I'll followup with a post upon initiating the repair. The cost of the part assembly was around $104 including shipping (as of April 2021). Many thanks goes to @davedogcaddy's video and the posts here - which have helped me decide to replace the entire assembly that includes the suspect rocker (zoom) switch.
I called the Canon Parts Order Desk at (866) 481-2569. I found their number on the Canon site here. The person working at the Canon Parts Order provided the part number after I supplied my camera model number, VIXIA HF G40.
The part number for my VIXIA HF G40 (given to me by Canon) is
Which seems to be the same part number for the VIXIA HF G30 as well.
05-06-2021 01:30 PM
The issue is caused by a small alignment defect in the rocker switch.
I permanately solved this without replacement parts by doing the following:
Reassemble the camera and check functionality.