I created a part from spur grar avaialble in toolbox. Then, saved the part in different location with new name.  I modified the part and saved it. Then I simpyy created an assembly file with only that part inside it, saved it and closed it. Now, when i opened the assembly again,the modifications done on part were missng and it reverted back to the original library part. But, if i opened the new part file, the changes are there visible. So, is there any way to solve this?