The Gaggia MDF is a decent little coffee grinder that tends to get a bad rap in serious espresso circles. It will never compete with the more expensive semi-pro grinders (e.g. Mazzer, Cimbali, MADCAP), but it can grind some decent shots with a little work. The most frustrating thing about the MDF is the size of the grind adjustment steps. With most coffees, a "5" is sufficiently fine to choke my espresso machine, whereas a "7" extracts far too quickly. This leaves the grinder with only one useable setting most of the time, and extration times vary significantly, even with adjustments in tamping technique.
There is an obvious cure for the above problem: remove the steps! Stepless mods for the MDF are well-documented (e.g. here and here). The most popular version of the mod uses several wraps of teflon tape on the threads of the upper burr carrier to provide some resistance to turning. This is a balancing act -- too much tape and it becomes difficult to adjust the grind; too little and the grind setting will shift during use. I never did get the balance right, so I came up with my own solution:
Basically, the rubber pad applies pressure to the hopper, which keeps the grind adjustment from slipping. I made this from parts I found in my shop, most of which should be discernable in the above pictures. Now my grind adjustment turns easily when I want it to and stays put when I don't.