Yes... I have experienced same problem.
I think it is for "Heat" or "Auto-tracking".
If you use HM30000 long time, the inner temperature of HM30000 is raised.
In that case, HM30000 can't playback normaly sometimes.
After having cooling period(remove the plug from wall outlet), HM30000 may playback normaly.
In case of "Auto-tracking" problem, you can use manual-tracking.
I think most of playback problems are cause by "Auto-tracking" error.
Toggle switch of "Auto/Manual tracking" is [+/-] buttons in left of front display pannel. [+] button and [-] button must be pressed together at sametime. Default is "Auto"(Tape input). Auto/Manual is toggled by each pressing.
In case that HM30000 can't recognize the tape, I use tracking toggle buttons. At the time of ("S-VHS" icon -> "D-VHS" icon), press toggle buttons(Auto->Manual). Then HM3000 can recognize the tape. And then if block noise is, press toggle buttons again(Manual->Auto).
I don't know if my advise is useful.