Can't comment on the park speaker but I've had a couple of success stories repairing rear blinds. Mind you it's not for the faint hearted. When the spring goes off it will chop the end of ya finger off it you got it in the way. Thing is I've not actually ever found anything wrong. All I do is open em up. strip down, clear em up and bung em back together again. Motors seems pretty bullet proof it's the gearboxes which give the grief. For some reason I've had better results using copper slip on the gears when I've rebuilt it than grease. Oh and if you go to the bottom of my garden and hunt around your find the motor/gearbox unit from one I launched after stripping it out and refitting it several times just to find as soon as I got it back together the ruddy thing jammed up again. Really is a pants design.