Can I use a metal spline on my washer?
4413ER1003B instead of 4413ER1003A?
The part that your unit calls for is the 4413ER1003A and the other may have a slight difference that may make it not work for your unit.
How do I know if the spline is stripped.
To determine if the spline is stripped you would need to remove the rotor assembly. Once removed you would be able to tell if the spine is stripped.