I tried it the first time with the 9.160 as I noticed some of my TTS voices are silent and again with the 9.004 I currently use on my device.
I need to log in my account to be able to download TTS voices and as far as I recall this was not the case in "the early days".
But anyway with a correct ttgo.bak present I was offered no TTS voices at all.
That was a bit odd for me and I closed Home and changed the values inside the ttgo.bif to the original values for my device and as I tried again with Home I got TTS voices offered.
Some I downloaded long ago like Kate for example are no longer offered to me at all.
But after several tests I can confirm that (at least for me) several functions in Home only work with correct values of the original Navcore inside the ttgo.bif.
The presence of a ttgo.bak or ttgo.ori with these values did not make a difference for me.
Same problem by the way for my mapshare : Home insisted that my device or map are not compatible with mapshare.
Only after changing the ttgo.bif and re-joining mapshare I was able to get the latest updates.
Quick fix however work like a charm.