vibrationle frontr from possib

hi there
i have got a 200tdi recently and was just checking the low box and diff lock and low box ok then put in diff lock seemed ok light come on took out diff lock light went out drove about 10miles and seems to vibate a lot which it didnt before,
one thing did notice was once turned on to my track diff light come on and off could the diff lock be cecauseing the vibration thnaks

Typically vibration from the transfer box would indicate either lack of oil or worn bearings. However, I have heard of this happening if the diff lock hasnt been used for a while - the selector tend to "seize" (for want of a better word) from lack of use. Have a look at the diff-lock operating mechanism and switch - make sure they are free and operating properly.
Hope this helps