As mentioned recently I made a backup of my Tumblr blog PMG to my computer, or thought I had. I had a Zip folder that insisted that it contained just under 8GB of data. Luckily I checked yesterday, and while still claiming to be 8GB, the folder was in fact empty, there was nothing inside it at all!
I had used the backup facility available on Tumblr itself. Perhaps I was just unlucky, but something had definitely gone wrong. Lucky that I checked before it was too late.
Then I discovered TumblThree, a program for dowloading or backingup Tumblr blogs to your computer (Windows). I tried it, and it works. I now have PMG and MGMG backups safely on my computer, each contains a number of text files, but most importantly, all the photos and videos. It took me a while to get TumblThree to work, initially I seemed to be faced with a number of buttons that did nothing, but you need to enter things correctly and do things in the correct order, then the buttons do work!
I have migrated to a FREE very Tumblr-like host bdsmlr, it is not perfect yet, but the Admin are working hard to set up and improve things. Currently they are trying to develop a tool to allow us to import our blogs from Tumblr before it is too late.