The hydraulic fluid needs to be changed in the hydraulic tank under the seat on a Massey Ferguson (MF) 1734E.
First, elevate the MF 1734E and support it securely on four blocks, one placed under each corner of the frame. You will then see the hydraulic reservoir under the seat.
Close the hydraulic by-pass valve and remove the fill plug from the hydraulic tank. This will allow you to drain the old fluid from the reservoir. Use a pan to catch the fluid as it drains and once complete, replace the fill plug.
Now, remove the breather from the reservoir and fill the tank with fresh hydraulic fluid until it reaches the full mark indicated on the dipstick. Put the dipstick back into the reservoir and reattach the breather.
Finally, start the engine and cycle the implements all the way up and down to purge the system before shutting the engine off. Check the fluid level in the reservoir then, and top off if needed.
You can now take the MF 1734E off the blocks and drive it as normal, ensuring to inspect and maintain the fluid level at regular intervals as suggested by MF.