Auto box problems

Hi guys.



I have a 54 reg 1.4 clio auto. I have just rebuilt engine after snapping cambelt. Engine is now running fine.



I have not had any issues with gearbox prior to snapping cambelt. Now gearbox light is showing at low revs as soon as a few revs are applied light goes out. Gearbox seems to operate nearly normal with the occasional jerky shift other than that seems fine.



I have read manual regarding top up or oil replacement. What I would like to know is if it's possible to refill box accurately without the use of oil temp diagnostic kit.



Can somebody correct me if I am wrong but as gearbox drain hole is fitted with a tube that runs inside , I believe all you will need to do is fill gearbox with drain plug removed until oil level goes over tube. Fit plug warm box up , remove plug , drain out excess oil.



I would appreciate some guidance from somebody that actually knows what he is talking about before I proceed with my hair brained scheme described above.



Oh car has done 74000 miles





Cheers



Scott



:d:eek::crazy::d