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/tOZRN2mxajk
Thanks for your input.