Extruder raising itself higher than normal

[Mega]

Recently, my printer has been messing up prints right from the start. When I start a print, it will heat up, then auto-home so that is can make sure it is the right distance from the plate. However, when the extruder should start printing, it will raise up a little more than normal and starts printing a couple mm above the build plate. This means that the tip of the nozzle is not the right distance from the plate and just has plastic gloop up on the end of the tip.

HICTOP, the company I bought the printer from, are insisting that I just need to adjust the sensors, which is attached to the extruder block that gets moved around, so that it is level with the nozzle. I've tried telling them that if I were to lift the sensor a small amount that the extruder tip would grind into the plate and if I lowered the sensor, the tip would just get farther from the plate. I've been trouble shooting this for a couple days and am starting to run out of ideas. I really need to get this printer back up and running because I have a couple days where I will have time to work on it. I also have the link for which printer I have and a small video of what it is doing.

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1 <-- This shows it as a wooden build plate, however it really has a heated aluminum one.

https://www.youtube.com/watch?v=V9_a4K9321Y

As you can see in the video, the printer homes in the z axis motors by lowering down to the corner until the sensor picks it up. Then it lifts up a bit to move to the center of the plate, but it doesn't go all the way back down when it actually starts printing and is a couple mm above where it should be. Any help would be greatly appreciated and welcomed.

[noiseboy72]

Check your slicing settings, as it may be that you have a Z move programmed in somewhere.

Never been a fan of auto-levelling. Seems to generate as many problems as it cures!