I'm glad I found this thread. I have had the exact same problem with HD.

Unfortuneately, it sounds like there is nothing to fix it for now.

I also notice that I have high number of corrected blocks.

I contacted TS and had them come out several times.  We have replaced the NID and splitter.

Had an I&R guy come out too. 

My corrected blocks are still up there and the HD issue is still there.

I thought maybe the high number of corrected blocks were the source of the problem, but I don't that's the case.

I observed HD when I wasn't getting any corrected blocks and the problem is still there.

For those who have experienced the same problem, please update this thread with any news.