You may need to lower the machine to its lowest incline position. That was the easy fix. If it is already in the lowest incline and still not latching then you may have a bent or broken return spring. A return spring is a coil type spring and if bent or broken will miss align the deck as it is returned to the up position. To fix it you will need to get a new spring. They are usually located near the front roller.
You will have to remove the lower pan covering. If you do not feel comfortable doing this, please call a qualified technical person.
Eric
November 2006