It's the same with new Nimh cell you charge at c/10. So in your case 0.3A.
Exactly what Neil has put is correct with the false peaking. Best thing to do is to charge them as softly as possible. So 0.3a for 10 hours. Use a timed charger if possible.
If you can access them measure each cell individually. If you have any duff ones it will help you find it now rather than later.
Charging at a higher rate can increase the risk of overheating and damage. Once the cells have been recovered and cycled you should be able to charge at a higher rate.
It's really complicated this Nimh charging
lipos are so much easier nowadays