Yanmar 1700B, Hydraulic problem

[Ola Farm Texas]

Have fron loader that has quit working. When tractor is started lifts in the back go all the way up and don't respond to down control. Loader may work for 10 or 15 seconds and then stops. Some times if the lifts in the back go down while parked. If they don't come up again when started the loader will work just fine. Any clues?I did notice the crome plated plunger about 1/2 inch dia , which is pushed in by the lift control for the back, stays in.

 

[winston1]

That plunger staying in is your problem. Need to pull it and clean it up. Yanmar Tractor Parts: THREE_POINT_CONTROL