[porthole]

You’ll have to drop the corroplast and check the gears and crossbar.
We have a DBRS3 but you can’t see the cross mechanism from the outside.

But, if you have a borescooe camera available you can probably peak inside through the rubber seal surrounding the rack.

We also have a ‘rodent seal’ around the cylinder which is held on with one screw. That might offer enough access to see that end.