Only 5 years late, but this just happened to me and I wanted to document my fix for anyone in the future.
1. Use winrar to open spr-mechanical_DE.bos in the core folder
2. After opening spr-mechanical, go into the "sprites" folder, go into the "robots" folder
3. Find "LoadLifter.spr" and double click on it
4. Windows 10 probably won't know what to open it with, so click "more apps" and select notepad
5. Before this next part, make a backup of the "LoadLifter.spr" file
6. Delete all the text from the file
7. Save the file and click yes when winrar asks if the file in the archive should be updated
8. Start up the game and load your save
When I did this, the load lifter body was gone and I was able to walk through the doorway. Once you're past the body, you'll want to use your backup copy of "LoadLifter.spr" to restore the sprite. Hope this helps someone someday!