IJoy message chair won't stay in the upright position

Had this iJoy chair for several years now - no problems - about a month ago it no longer wanter to come back into the upright position with out a helping hand. Then it wouldn't stay in the intermediate positions when released but immediately fell into full recline as if the shock/spring assembly(?) had become "detached". Finally it won't stay in the upright position at all and immediately falls back to full recline.

Went into the arm of the chair (by removing the release switch/panel) - looks like the "shock absorber" is there and moves along with the chair back - and the cable release is working - so I'm guessing the valve it actuates on the "shock absorber" is broken (in the open position). Is this most likely the case and can a replacement switch/part be obtained and if so how? Looks like the entire anchor where the switch is can be released with a single lock nut, so I'm game to try and replace it if that's all it takes to restore normal position locking - thoughts, suggestions, places to contact are much appreciated. Bruce