rear spoiler problem?!

[mos]

Hi i am a newbie to the forum and have had my 05 boxster S for just under two months

Ever since i bought it its had annoying fault that seems to disappear after the car has been running 10 minutes or so

there seems to be a knocking noise from the back of the car that is quite prevalent at first and gradually diminshes until after 10-15 minutes of driving its gone altogether

i took it back to porsche, but of course the car was warm and they could find nothing wrong

i took it to a friend of mine who is a mechanic, put it on the ramp and also we could not find anything.

once we took it off the ramp we happening to be playing with the manual operation button for the spoiler and deployed it.

once it was deployed we noticed that one of the hydralic rams seems to have some play in it and also seem to make a knocking noise.

with someone outside moving the spoiler, if someone else is in the car its sounds a lot like the noise i am hearing.

has anyone else had problems with the spoiler knocking, it works fine deploying and retracting on the move as it should, but i cant get my head around why the noise would disappear after the car has been driven from a while

could this noise be the spoiler or am i mistaken?

help

thanks

mark