loader blade issue

[jersy Al]

Hello...........first time on forum. I have a late 80's B8200 with a loader and a back blade. Recently, with the blade attached, when either lowering the loader or tilting the bucket up the back blade goes down. As soon as you stop using the loader the blade returns to the up position. If you VERY slowly operate the bucket or loader the back blade shakes but doesn't go down. I've adjusted the implement control valve without any improvements. I've searched the interweb, an operators manual along with a service manual without success. I have no issues on the tractor without the back blade. It's just annoying me. Any suggestions out there? thanks

 

[Fedup]

Leave the loader on the ground. Raise the blade full up and shut the engine off. Don't touch anything else. Does the blade drop to the ground? If so you must have a pretty bad leak in the three point lift cylinder or a related circuit.

 

[North Idaho Wolfman]

Fedup has a good first test.
Also check that the feed back linkage is properly adjusted and operating.

Is this a OEM loader and OEM loader hookup.
Is this a new issue?