75-300mm Lens won't lock onto my EOS Rebel T3

[pankers22]

I've had this camera and lense quite some time, and used it a lot.  After a long period of no use, I got it out to make sure everything still works good.  The camera and standard lens works well.  However, when I try to snap on the 75-300mm lens, it won't "click" on correctly.  It will get to a point where it will stay on and work, however, the Autofocus doesn't work, so I feel like it isn't on right, and as I said, it doesn't click on right like it should (and like the standard lens).  Nothing looks broken on the lens itself.  Obviously nothing broken on the camera because the standard lens goes on and works properly.  It still looks relatively new, no idea what could be going on.  Anyone else ever come across this?

[Waddizzle]

Check the screws on the camera and lens mount are fully tightened.  Do Not Over Tighten!

If the lens has failed to work properly, then it may have to be replaced.  The cost to repair the lens far exceeds the cost of a used or new lens of the same model, $100 to $200 USD, if not less.

If you need a replacement, then I recommend the EF 70-300mm f/3.5-5.6 II USM, or the much older EF-S 55-250mm IS STM lens.

[pankers22]

The screws are all tight.  I feel like if it would go on correctly, it will work properly, but a physical issue is preventing it.  As I said it looks perfect nothing broken.  Very confounding.

[Waddizzle]

If you have a local camera shop, then let them take a look at it.  It could be something very minor, just as you’ve suspected.  

Otherwise, I’d simply replace the lens.  It is not one of Canon’s best efforts in terms of image quality.  The primary design goal seems to have been teaching beginners about lenses, not high image quality.  Most of the time these camera kits will sit in a drawer or closet unused for years.  This is why they are not designed for high IQ.

[Waddizzle]

Here are some current selections in the Canon USA Online Refurbished Store.

https://www.usa.canon.com/shop/p/refurbished-ef-75-300mm-f-4-5-6-iii 

https://www.usa.canon.com/shop/p/refurbished-ef-s-55-250mm-f-4-5-6-is-stm 

https://www.usa.canon.com/shop/p/refurbished-ef-70-300mm-f-4-5-6-is-ii-usm 

The last one is currently out of stock, but it is highly recommended.

[pankers22]

Thanks for the tips.  I actually got it out to sell the package, so I'll see if I can find someone to take a look at it first.