Accessed via the right click menu.
(Edit: Wooops you're on a mac, hmmm I'm not sure how that works with macs)
(Edit2: Entering properties in the command line should do it)
ok so this is what i have done. i found a friend who has autcad 2008 .. opened the file and command: FLATTEN .... it worked for one file but not the other... I not sure why. any suggestions or anyone willing to try it out? also i would like to find out how to fix this problem without depending on older versions...
Thanks for all the help.
lets keep trying
Once you export them this should work
what i suggested was only for MEP 3D objects. i saw your uploaded drawing and i would suggest you to make the start/end z elevation equal. i have tried it and it works (see attached). you have to spend some of your time since you cannot select all in one go so you have to select by group or each line.