I experienced similar problems to the ones posted throughout this thread. (Using LT2013)
The WBLOCK technique worked for me most of the time too, however, when it failed, the SAVEAS DXF worked for me. Note there is no longer an "Export to DXF" in LT2013.
I use COPYBASE quite a bit to copy objects from one DWG to another and that seems to pollute the target DWG the most. Making sure your blocks are completely clean prior to inserting them is a great first step.
Other additional thoughts include;
1. For those of you using ACAD variants (Civil, Arch, MEP, etc), I'm curious if any Object Enablers in "standard" ACAD may contribute to any drawing corruption. Or for that matter, cause inconsistencies between different users.
2. With regard to LINETYPE corruption/pollution; since custom linetypes (many Civil drafters use TEXT within their line types such as --GAS--, --OHE--, --UGF--, etc.) include the TEXT styles used in those custom linetypes may be contributing to the corruption.
Hope that helps.
I tried a number off the suggestions, the one that worked for me was the dxfout, then dxfin. I tried to use the layer translator, but I can't seem to find it in 2012LT.
Please be more specific with what you tried and the ACAD version you're using.
Try the following:
1. _DXFOUT and save the file.
2. Close the file.
3. Open the DXF you just saved.
4. Save as a DWG...now check for the linetypes. If that did NOT delete the linetypes continue on to step 5.
5. WBLOCK the entire drawing to a new file name.
6. Close the file you have open currently.
7. Open the new drawing you just wrote with WBLOCK.
8. Now check for the linetypes. If that did NOT work, please post the drawing and/or provide the additional details about your platform/version, etc. It may help to close all other drawings and perhaps even try all the above steps on a different machine if you have access to one.