7045 Air pressure sensor; hydraulic return

Finally got all the 7045 electrics & guages working apart from indicators (not relevant for me - I'm never on the road), PTO light & air pressure guage. I can't see where the air pressure sensor is - on the parts diagram it looks to be at the rear of the air tank, but I can't identify it, could it be anywhere else?

Since I cant find a way to post a picture, Ill have to describe the following.

For a free hydraulic return: There is a large filler plug under the seat (currently removed), but the cab floor & seat base fits too close on top of this to enable a return to be fitted to that. On the next level down, where the banjo bolts for the existing hydraulic connectors are fitted, there is at least one large bolt (over to the handbrake side) is this a plug? I am loth to undo it without knowledge in case it secures something large & important to the inside of the transmission case!!

The gearbox oil filler/dipstick pillar: does this unscrew from the gearbox topcover? If so I could possibly weld a branch onto that to screw in a hydraulic fitting to provide a free return - has anyone done this? This looks to me the easiest way to achieve a return port.

The air pressure sensor is on the tank where the steel pipe comes out, it is a round steel switch with wires attached.

The return pipe on our old 6718 came out from under the seat, it was an elbow connection and the pipe went forward and around the seat and out the back. If the dipstick collar is long enough, all you need is to drill a hole and weld a 1/2 straight connection onto it.

Thanks for that - I'll have a go at finding the sensor tomorrow if this wind & rain ever stop!
I'll have a go at unscrewing the dipstick pillar too - that seems to be the easiest way to get a return port sorted.

You could always drill gearbox cover lid and weld in a hydraulic connection.

Trouble is the gearbox cover is under the cab floor? Only small hole for dipstick pillar & between gearlevers where a previous owner has cut away a section (access to the detents I presume).
I'll have a good go at unscrewing the pillar because today (hurray!) I finally got all the electrics working including the air pressure guage & the second fan blower

The floor opens off around the middle piece at the hump that's between your legs, there's bolts either side of the gearbox, we had 7245 and that's where it opened.