24-105 diy repair questions

Hello all,
I recently bought a "g" rated 24-105 f4l from adorama for $349. The exterior of the lens is in mint condition but it has quite a bit of dust specks under the front element. Removing and cleaning the element seems pretty simple and straight forward after watching a couple of youtube videos demonstrating the procedure. Here's my issue: when I removed the trim piece I found that each of the 3 screw slots had 2 screws in them instead of one. Does this mean the lens has been serviced or adjusted in the past? In the videos I watched each slot only had 1 screw a piece. I stopped there and didn't remove the element.
Here's a video I watched: https://youtu.be/tOZRN​2mxajk
Thanks for your input.

The video link you provided was for the EF-S 17-55, not for the EF 24-105L.

Correct. But the disassembly is the same.

Are they the screws and are the extras the eccentric pins referred to in the first paragraph at https://canonrepair.wo​rdpress.com …-the-aperture-flex-cable/

Just make sure to put that front element in same position and it's just fine.

John from PA wrote in post #18484508
Are they the screws and are the extras the eccentric pins referred to in the first paragraph at https://canonrepair.wo​rdpress.com …-the-aperture-flex-cable/

No. If you look at the video I linked , there are 3 slots around the front element . Each slot has 3 different screw holes, but only 1 screw per slot. My lens has 2 screws per slot. Twice as many in the video. I was just wondering if this is common, or if the lens has been adjusted or messed with in the past.

trekgod3 wrote in post #18484614
No. If you look at the video I linked , there are 3 slots around the front element . Each slot has 3 different screw holes, but only 1 screw per slot. My lens has 2 screws per slot. Twice as many in the video. I was just wondering if this is common, or if the lens has been adjusted or messed with in the past.

After reviewing https://wordpress.lens​rentals.com …a-few-easy-lens-dustings/ and specifically scrolling down to "Canon 17-55 f/2.8 IS EF-S Front Dust, Also applies to: Canon 24-105 f/4 IS, I would suggest you replace the screws as you found them.

You might also look at https://wordpress.lens​rentals.com …/front-element-scratches/.

John from PA wrote in post #18484845
After reviewing https://wordpress.lens​rentals.com …a-few-easy-lens-dustings/ and specifically scrolling down to "Canon 17-55 f/2.8 IS EF-S Front Dust, Also applies to: Canon 24-105 f/4 IS, I would suggest you replace the screws as you found them.

Yes. I plan to. However, my original question was regarding why there are 2 screws in each slot when all of the videos and pics I've seen all have 1 screw per slot. Has anyone who's removed a front element found more than 1 screw and why?

The article at the wordpress.lensrentals.​com link I provided was written by Roger Cicala who is either the owner or founder of Lens Rentals. Why don't you use their "contact us" and see if you can get some guidance from perhaps Roger. They also have a blog although I'm not sure you can add a topic or add content to an existing topic without registering.

https://www.lensrental​s.com/contact

I have only ever seen 3 single screws in the front ring and the 24-105 service manual only refers to 3 screws so I would say that it has been taken apart before.
There are multiple screw holes to enable a wider adjustment range.
Incidentally if the front element is put back in the wrong position then it upsets the focus regularity, it should be adjusted by focusing on something at 24mm then without altering focus set the lens to 105mm and adjust the front element to get it into focus.

If you want a copy of the service manual feel free to PM me.

I cleaned mine for several times already. The number of screws in each slot in my 24 105 are just exactly the same as yours. I bought it brand new a few years ago so I think your copy is ok. In my opinion, one way to determine if the lens had been serviced is to check the head of the screws. They should be free from scratches or deformation.

Thank you both!