MTH, in collaboration with the AGHR Model Railroad Club, has researched, tested and developed a preventative modification for all TIUs, although Rev. L TIUs appear to be those most often affected, to prevent failure of the DCS signal generators in heavy use situations. This solution is discussed in the attached document, Service Bulletin 05-22-18a.pdf. You may view or download the document using the link at the end of this post.
Note that if you are not an MTH Authorized Center technician (ASC) and you damage any TIU while attempting to install the modification, any and all warranties regarding the TIU so affected are voided.
Many thanks to MTH and AGHR for their diligence in bringing about this modification.