Came about this post in a Google search for Torx size...LOL Seems like a good thread. I already took mine apart but figured while I wait for the new digitizer from Hong Kong I would order the Torx set.
Okay so your probably wondering how I took it apart then. Simple I dremeled a small flathead eye glass screwdriver to the size...LOL I have tons of eye glass screwdrivers (a side of the family owns a huge Hardware chain in MI so stock holders get grab bags at the annual meeting of products)...LOL So I don't NEED the torx but for the $8 on Amazon for a nice set why not order them. I've needed them for OTHER electronics (seems to be the norm now).
I think I paid $18 included shipping from Hong Kong direct from manufacture. I believe its the manufacture selling them hence the cheap price. If I recall the ebay listing it said includes the screen too which the first post says is an extra $50. So that might of changed now.
I got my Zumo in 2007 till 2012 it lasted, that is much longer then I thought the GPS as a whole would last. I have had to replace the battery once and the GPS mount once. I did notice that one of the buttons had a light crack around it...probably will dab the inside of the button with black silcone but you probably will want to look at those while you have it apart. You could not notice the crack from the outside.
If I can get 5 more years out of this unit then I would say that it paid for itself. If I recall the wife paid $580 on Black Friday for this.