clean up Dust inside letus ?
 

Do you know how to open the letus to clean up some dust inside?

LETUS35 DISMANTLED - http://www.youtube.com/watch?v=yugfv4ZVXgg

There are a few differences on the Letus35 shown in the clip. Don't take the mirror enclosure apart as is demonstrated at the end of the clip. there is no need.

Your visible dust problem will most likely be confined to the groundglass screen or the reversed biconvex lens you see being prised out of the front of the flip enclosure.

The tweezers on the support pillar only demonstrates a little tweak sometimes used to tune up the groundglass movement if it becomes too linear. You don't take the groundglass panel off the pillars. They are a permanent fixture.