i have a 2l w reg aswell with a single click when manouvering in car parks which has been diagnosed as the valve in the rack being worn due to never having had a fluid change. new fluid now though and its improved.

have you definately got fluid in? with it suddenly going stiff i'd assume its the pump failing but with the clicks aswell i recon its your rack.

straight forward job to replace but requires dropping the subframe. can be done at home to save money and also i'd suggest getting a salvaged rack off a lower millage car.

most dont fail, just the odd few seem to in my experiance so a salvaged one with say 60 or 90 day warrenty should be fine as any faults will show up in that time.