the short answer is no - no solution but .....
its not hardware - or if it is it is self- healing.
many if us are having this same issue - my wife's sp4 type cover stopped working about a month ago and i tried everything to get it to go with only one brief episode when it worked until....
we were packing up to go on holiday and she took her sp4 together with a Moku bt type cover ( which works very well btw ).
just before leaving i tried the msf type cover and bingo - it started working and has continued to do so for the last three weeks ( if course it may stop doing so at any time ).
it seems to be a firmware issue and/ or something to do with the attitude sensors in the machine.
as i posted before, the only things i did which may or may not be relevent was to play around with rotation lock with/ without the type cover attached. also the psu failed and i had to get an oem replacement. unfortunetly i cant remember whether this was when it started working again but it was within a day or so.
richard