Was it particularly cold out when that happened?...My bucket is very slow when it is first started in cold weather...as the fluid warms up it gets better...that stuff looks like butter in that opening you have there

 

I checked before I drained today as it's the warmest we've been in a while, pushing 70° and same result. And yes, I'm getting some water in the fluid from the shifter boots but that's not a new issue and I don't think it's the cause.

 

Might be time to change the fluid

 

That's happening either way, had to drain it all to get to that picture but now have no clue where the filter is..

 

is there a parts diagram that shows the setup and how that filter is supposed to be mounted?
for a filter to be useful, there has to be a pickup and a return... I see nothing of the sort in the picture... are you sure that's where the filter goes?... maybe it's just an access plate for inspection or adjustments?....

 

I agree with wally...I don't see how even a screen would be fitted there...you are going to have to get underneath the tractor and take a look around the trans and see if you spot a filter sticking out somewhere ...also ..will the 3 PH lift a weight?...and if it does that does it lower quickly when released?..is there a speed control for the 3 point ..I know mine has one

 

I found prior articles that the strainer was behind the 3 bolt triangle plate under the tractor, no good diagrams. I've now discovered their are multiple versions of the 285 lift pump and some must be accessed from top or side but all are inside the case.

As far as lifting, it will lift my 7 foot bush hog, but brutally slow ~2 minutes to go all the way up, it drops quickly

 

That tractor is fairly high isn't it? You should be able to slide under and get a look at the trans and see either another inspection point or a spin on filter...I would think

 

Yeah, lots of room underneath but seems I have to go in from the top (see below).. only external filter is for the remote hydraulics. Sure seems like a horrible design decision from Massey

From another forum:
I know this isn't what you're hoping to hear, but on the older tractors, yes, with that left hand side cover off, the filter can be reached. It's no picnic, but can be done. However, with the lines and fittings pictured, that cover won't come off without first removing the lift cover and disconnecting the internal lines attached to the fittings on the inside. Those are actually bulkhead fittings with lines attached both inside and outside. Removing the right side cover is no help because the lift pump control linkage (and other stuff) is on that side. By the way, dealing with that control valve linkage is part of the lift cover removal process