I updated to 9.051 because I understood that RDS/TMC reception would improve - it didn't. So, as I prefer the menu structure of 9.026, 'Operate my GO' worked (as did everything else) I have been trying to get back to that version.
What I have:
TT GO 910, App 9.026.483454.1, OS 473972, 64MB RAM (free: 4.4MB, GPS v1.20, Boot 5.5259Map: Western_Central_Europe_845_2645
I got to this stage by deleting the root files and downloading Navcore.9.026.gi.CAB-navcore-GO.cab from ...