What's the best way to speed up my slow sunroof without having to go thru the process of removing the back window?

In colder weather it is unable to move or moves very slowly, and 9 times out of ten needs a hand closing, but when the weather warms up in the 20c's it moves great but still slows down a little in the middle. when it's cold it won't go any father than the middle.

I suspect this is a lubrication issue; what with the tempurature factors and all.
can the tube be lubed with something like a penetrating grease (not fluid)? or something?

thanks

Ryan

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RIP: 80 300SD
RIP: 79 450SEL
2002 E430 4matic (212,000km)
2002 ML500 'sport'

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