Case 580b ck

I know I’m betting a dead horse here cause there has been a lot of talk on here about the case 580 not moving, but thought I’d ask anyways. I just picked up a 1973 case 580B CK backhoe. Noticed the power shuttle fluid was strawberry milk color so I flushed it a few times with new fluid and I got it to move finally since it wouldn’t when I got it . What it does now is I have to let it warm up before it will move at all in morning and than it comes in and out of movement and I have to push pedal in and out to get it to move again. I changed the filter but is it worth checking the pickup tube screen or because it’s moving at all does that mean it’s prob something else ? Thanks