I was sitting around thinking,.. I know how to play a mandolin, I should get one! (sometimes you can be too cheap for your own good)
Anyway the action on my new mandolin was a bit on the high side. Since this mando didn't cost me that much I decided to lower the action on it myself instead of taking it in and paying money for someone else to do it. So I marked the position of the bridge with tape before removing the strings as you can see in the photo. I wanted to make sure i'd have a reference point to put the bridge back on as I didn't want to have to slide it around as that could scratch the finish. The octave is half way between the nut and the bridge so you can move the bridge back and forth until the octave is in the right place, but it helps to mark it first. Plus I tuned my guitar to my piano so that I knew what pitch E would be.
The bridge is in two pieces. top and bottom. I could see that if I removed material from the bottom of the top part I could lower the action. I did that by sanding down the bottom of the top part of the bridge. I realize that's kind of confusing. I left the low G string on (loose) so I could center the bridge when I re-strung it starting with the high E string. (usually when I change strings I'll do it one at a time, and not all at once, but since I had to remove the bridge I took them all off except the low G) I didn't bring the strings up to pitch until I had them all back on and I slowly brought them all back up like you would tighten the lug nuts on a car wheel when changing the tire. The results were really nice. It made the mandolin much easier to play as it doesn't require as much effort to push the strings down now. A lot more fun to play!
I was surfing and found out I should remove material from the foot of the bridge and then raise the turn wheels to get the strings to the right height. So I've done that and you can see what I've done HERE