Mini Excavator Thumb Installation on a John Deere 27C.. Fitting the thumb, welding the mounting tab and hooking up the hydraulic circuit. This should be similar to thumb installations on most excavators and backhoes. Timestamps if you like to Jump Around: 00:00 Showtime Fab Thumb Intro 00:55 Start the installation 03:00 Snapring Common Pin 05:44 Hydraulic Spreader Action 09:44 Main Thumb pin installed 12:00 Hit Snag. 4 Hours into install. 19:50 Welding begins. 29:20 Hydraulic Hookup 31:06 Thumb Operation