first layer - FW update  

OK, let's try the easiest one first - I have seen this occur when the smooth sheet was not fully pushed into place and then shifted against the retaining pins.

Cheerio,

RE: first layer - FW update

hello. every time i push the plate correctly in position. so thats not possible.

next 

How are you cleaning your build sheet?

Cheerio,

RE:

hello, i wrote with support and they advised me to clean the sheet with warm water and dishwashing liquid. i did it and now it seems to be good again. 

before i always used handgloves when i touch the sheet. sometimes IPA. but never the advised method. only one time, after the problems occured, i used acetone. i wonder how good the results now are.

but i flashed the firmware with v6.3.4 too. so its not sure if only the washing was the solution. 

do you know if (and how) i can deactivate the info about new FW available every time i want to start a new print? its annoying.

so for now the problem is solved. lets have a look how long it would last. cheerio