40D focusing issues

My 40D's focusing just started acting up. I've nailed it down to the center focus point, the one directly above it, and the one left of that one. All three fail to lock focus. The other focus points seem to focus fine. Tried several lenses with the same results. I took a blower and blew out the mirror and sensor. No difference. Anybody ever have this or similar problem. It probably has 40,000 actuation's or so.

No one.... Just tested again with my 70-200 F4, same as above. Center and two other focus point not focusing. Other points are fine

You are choosing the FPs one at a time in One Shot mode and 3 won't lock focus but the others will? Does the lens "hunt" and then give up(flashing green dot) or not even try?

Yes! Choosing them individually. In one shot mode. Three of them won't lock focus. The lens tries to focus with all 3 (using one at a time) but never locks on. The focus confirmation light flashes and doesn't stop flashing with those three points. The other points confirmation light stops when it has focused.

After looking again. It's the center point and the top three. I took out the focus screen ( I replaced the original with the S screen when I bought the camera years ago), just to make sure it was seated correctly and blew it out again. Same problems.

Did you clean the AF sensor? It's in the bottom of the mirror box. Cleaning the screen won't do anything; it's an image but it doesn't play a part in the AF work. Basically the light path for the AF activity is through a semi-silvered part of your reflex mirror, off a secondary mirror and down to the AF sensors. When the primary reflex mirror is up, the secondary mirror is folded up too, so there isn't really a good way of cleaning that. I suppose, if you're daring, you could try blowing off behind the primary mirror while it's down, but personally, if blowing off he AF sensor didn't rectify the situation, I'd send it to Canon (or a local, reliable, camera repair shop).

We have a dependable repair place here locally. I'll probably take it in. I was just wondering if this was a symptom of one thing or another failing. Southern Photo Technical Service
here has a web site you can ask questions about repair. I did so the other day but it's Easter weekend. Maybe they can give me an answer

Thanks

Did you get an answer from Southern regards your problem?

I left a question on their site but never received an answer. I need to take it in and have them look at it.

Took it in to Southern Photo today. He hadn't seen this issue before. I left it with them. Probably won't be able to seriously look at it until Monday.

I wonder how much repair will cost compared to purchasing a used camera, perhaps even newer than the 40D.

repair costs for the 40D through Canon are higher than buying a used 40D, based on my last attempt to send in a 40D. they will quote you, and you can decide then to get it fixed or not.

I would have tried a factory reset to see if that sorted it.

I did a reset. No difference. The guy at the shop also suggested that but I had already done that. I told him I could buy a used 40D for under $300. He said it shouldn't cost $300 but he could see $200. I would like a new camera. 70D maybe. I don't have the extra grand right now.

Southern Photo said it will cost $230 to repair. Replace focus points. Probably won't fix. Just use it as is for the time being. My birthday is coming up. Maybe I'll get lucky.