[leone184]

Some openers have 2 adjustment knobs, or screws on them. One is for the pressure or force, the other is for travel. It sounds like the door is traveling too far. I don't know what brand of opener you have, but mine has 2 nylon screw heads on the back of the motor housing. (one for each) If you took the slack out of the chain, it makes sense that this is whats happening. The door is probably going up just a little farther than it did before.

By the way, once you solve the problem, make sure you turn the pressure knob back down. It should be at the lowest setting possible to close the door properly. If the door should come down on something (like someone's foot) it will press harder before it reverses. It also puts a lot more wear and tear on the opener and the door.

leone184