Took Andy's advice and searched the manual, found the description of operation, diagrams and testing flowcharts

Amazing resource available at your fingertips

What I have not found is symptoms that may indicate air solenoid failure, don't feel like pulling the bike apart is it's not broken, but I would have no clue if it is since I never ridden or even seen another NSR250 up close. When I purchased my RG500 the power-valve servo was fried and for the longest time I just assumed that it supposed to run like sh*t all the time till it gets on the pipe, having never ridden one before I had nothing to compare it to. last owner had it for 15 years, didn't know either!