I would first check the level and condition of the power steering fluid. If the level is low or you see a lot of air in the system top it off and recheck for the issue. Other than removing the axle as you suggested there is very little they would have done with the power steering system that I can think of to cause a problem, in fact I’m sure they never even removed the front wheels. If you do find the level low or full of air you might want to put your eyes on the PS rack and it’s hoses to see if you can identify any leaks.