I am basically going to chronicle what I have learned from the wonderful guys on http://www.subguns.com/ - special thanks to Bob Naess at Black River Militaria.  First, make sure you have stripped your gun, and thoroughly cleaned and lubed your gun.

        The first time you shoot your Maxim, make sure you have high quality ammunition, try to erradicate as many variables from the equations as possible (Yugoslavian 8mm works well).  Load your belts correctly, since most will be using Vickers belts - load them like the rounds labelled "good" in this photo:

        Setting the fusee spring can be tedious, so its best to take an analytical approach to the matter.  I ended up using a totally illogical approach, with no ryme nor reason, and had too many variables to start with, dumb, but I hope to help others start on a better footing.  I don't remember where I read the following instructions, however, they work, so I shall pass them on to you. Start with the spring tension at a high setting, 65, or so.

Load the gun, and if using a bipod, make sure its well supported (misfires abound when you "limp wrist" a Maxim) - and fire. It will likely fail to fully cycle - will fire 1-2 rounds then quit.  When the gun doesn't fully recoil, it will not move the belt over so a new round may be picked up, since when the gun is loaded, there are 2 rounds on the lock, it will fire those two rounds and stop.  Loosen the fusee spring by three turns (thats three turns clockwise), reload the gun, and try again.  If the same thing happens, repeat loosening/reloading/firing.  Once the gun starts firing continuously, you have reached the point of maximum firing rate for your maxim using that ammunition and muzzle booster.  You may continue to loosen if you desire a slower rate.  If you loosen too much, you'll experience a failure to fully lock - the extractor ears will fail to raise up and grab the next cartridge (see below).