Monorail Lighting

How do I change an MR-16 halogen bulb on a monorail system?

This is really hard to explain, but what I think I have is a low voltage monorail track system. it has several different kinds of lights attached to it. Some are easy to change the bulb as you just pull the bulb out. But 1 of them has a very tiny allen screw that I recall being told I have to unscrew first. So I have the tiny allen wrench. I unscrewed the screw, so now I have access to the bulb, but the bulb wont just pull out. There are 2 tiny holes on each side of the white plastic piece that is covering the MR-16 pins. The wire that comes down from the monorail splits into 2 wires that come down into the top of the white plastic piece.It seems like I would have to stick a pin or something into the side holes that I described to release the bulb? Maybe that is not the case and all I have to do is pull really hard to pull the bulb out, but it seems like it might break if pull with too much force. if you cant figure out what i am describing maybe i can email someone a picture of this.