1 gear Strange rattle.....

[tt2008]

Hi,

I got my Boxster on the road yesterday - first time this year :-)
But when I start driving in 1 gear, there are a strange rattle sound - I think is it from the transmission....??

The sound is only in 1 gear, there are no sound in 2-3-4-5 gear
It is a "clicking" sound and when I drive faster i 1 gear the sound is more and more often...

If I take the clutch the sound disappears...

I have checked the exhaust and heat sheilds but it seems to be fine.

The Boxster is from 1998 2.5l with 130.000 km on the clock.
Are then known to have a weak transmission or does anyone have another idea of what can be wrong.....????