nsa310 and nsa235-V2 admin doesn't have write access to admin share folders

Strange. The package contains only two files: /opt/etc/init.d/S09ZyXELSambaReplacement and /opt/etc/samba/ZyXELSambaReplacement.conf. That's it. Don't see what it matters to reinstall these. There is no init script which sets things up. The only 'nasty' thing is in /opt/etc/init.d/S09ZyXELSambaReplacement, on start it executes

# Move /opt/var/lock to ramdrive, else the maintenance of browse.dat will keep the disk awake
if [ ! -h /opt/var/lock ] 
then    
mv /opt/var/lock/* /var/lock/    rmdir /opt/var/lock && ln -s /var/lock /opt/var/lockfi

but that is executed on each start. (And is the reason the script is S09, to start it early, an nothing is using /opt/var/lock yet). This scriptlet only fires once. When the symlink is created, it stays.

I can imagine that sessionid.tdb is put there. Have you found where it's stored?

could it be related to the drive going to sleep after time of idling?

also i've found the sessionid.tdb file to be located in "/var/locks/"

How? What is ruined?

That is more a description of the result of the damage than the damage itself. As far a I know 'cannot open sessionid.tdb' can be a difficult way to say samba isn't running.