Cat 416

Hi Guys I am new to this forum. I am from Elmvale on Canada eh! I am seeking some advise for help with a Cat 416 Backhoe. I can post the serial number if it would be needed. This is late 80s early 90s model. It has the perkins engine and spicer 4 speed transmission. The trouble I am having is with the 4wd engaging. I have check the solenoid and it gets power and does activate. It would seem this moves a valve of sorts as when I would push on the plunger in the transmission it does not activate any gear so to speak. I do know there is a suction screen in the trans which I will look at to see what is in it. I have changed the transmission fluild and filter end of last summer. unit doesn't get used in the winter. I did change the front u joints and it seemed it was shortly after that the 4wd did not work. when the machine is in the air the front will engage and turn if there is not load on the wheels when the load is introduced the wheels stop. forward reverse seem to work fine. I am looking for some direction as to what to look at and for. Does anyone have a parts breakdown or pages from a service manual. Thank you in Advance.

Brady

Cat 416