Thanks to you both. The 980001156 part number on the Eurospares illustration says "Power Unit and Tank....valid F1" and shows a hydraulic reservoir, so I guessed it to be associated with the gearchange. No pressure= no gear change, no clutch separation and no start ! The manual shows the (engine oil) sensor on the rear right cylinder head. More homework needed............
This is what I got.....
http://www.eurospares.co.uk/searchResult.asp?find=&M=&Mo=&A=&B=&S=135940
Cheers, Miles.
Yours is on the engine Miles......................has a 100% chance of being right compared to mine!
P