Wiper transmission assembly installation

Hello,
I am in the process of installing a new wiper assembly after my old one was old and could not be attached to the motor. I have gotten the assembly in and have gotten in to work and rotate around when the wipers are not attached. Once I attach the wipers they are not on the correct rotation and begin by going down first. I have looked it up and it seems like the situation where they would have to start their rotation at a 45 degree angle. How would I correct this? Additionally, and perhaps more importantly, when it is running for a while, the nut that is attaching the motor and assembly starts to loosen until it becomes too loose to move the assembly in general. I am also wondering how I can amend this? Thank you.