A little late to the party but I had these problems on the actuators on my 400DA (front window and hatch). That hatch was really heavy. Two things contributed to the issue.
First was simply the O-rings at the end of the ram housing. The aluminum end cap the O-rings set in gets a little corroded plus over time the O-rings become gooey and sticky and the ram just will not slide smoothly across them. Easy to take apart - I cleaned up the grooves in the end cap and replaced the rubber O-rings with Teflon O-rings. Problem solved. An occasional squirt of silicone lube...
The second issue is all of the electrical current to the actuator motor runs through the helm switch and over time the wiring, connectors, and switch just can't pass the current and that motor sees a significant voltage drop causing it to bog down and not have the torque to open the hatch. I installed a reversing relay assembly in a little enclosure and sourced motor power directly from the main breaker panel. The helm switches only operated the relays. Way back when I posted about that relay assembly.
First was simply the O-rings at the end of the ram housing. The aluminum end cap the O-rings set in gets a little corroded plus over time the O-rings become gooey and sticky and the ram just will not slide smoothly across them. Easy to take apart - I cleaned up the grooves in the end cap and replaced the rubber O-rings with Teflon O-rings. Problem solved. An occasional squirt of silicone lube...
The second issue is all of the electrical current to the actuator motor runs through the helm switch and over time the wiring, connectors, and switch just can't pass the current and that motor sees a significant voltage drop causing it to bog down and not have the torque to open the hatch. I installed a reversing relay assembly in a little enclosure and sourced motor power directly from the main breaker panel. The helm switches only operated the relays. Way back when I posted about that relay assembly.