would hope you've done this by now, but having had the pleasure this weekend here's a quick guide..
1. ensure wipers are in the rest position
2. remove black plastic caps from wiper arms
3. remove retaining nut from wiper arm (13mm socket), remover wiper arms
4. open bonnet and undo the 3 phillips head screws that secure the plastic scuttle panel
5. disconnect the black rubber washer pipe from the scuttle panel
6. pull scuttle forward and then lift up - note the clips underneath that locate under the windscreen (important for re-installation)
7. disconnect wiper motor wiring at the connector (lift tab and separate)
8. undo the two bolts that hold in the entire wiper mechansim to the body - 10mm nuts with large washers
9. slide mecahnism towards the passenger side to disengage the rubber gromment at the front of the motor, then shuffle the whole mechanism out
10. connect new/replacement motor to the wiring loom and operate the motor to ensure a) its good an b) its turned off at its 'rest' position
11. remove retaining nut and washer from the old motor spindle (12mm nut) - its important to keep the mechanism aligned to the splined spindle, so either hold the mechanism in a fixed position or mark the spindle and mechanism
12. remove the motor holding bolts - 30T torx head - to release the motor from the mechanism frame.
13. rebuild is exact reverse - once the motor is mounted to the mecahnism its advisable to test it to ensure the wiper arm spindle operate as they should (saves time removing it all if you've got the motor spindle spline wrong !)
14 whilst you have the mechanism off its advisable to clean the joints and regrease (you can lift the rubber boots on them to get fresh grease in)
Stand back and admire your fully operational, quiet wipers !
PS - a new motor from Fiat is around £155+VAT ! There are several variants (mainly electrical connection), so check you have the correct one before buying, i had to wait a few weeks for a suitable Denso one to appear on eBay.
