Lift not working 6718 Zetor

Just bought a wee Zetor 6718 good wee tractor seems to be going well good breaks starting of the button ,however I lifted one round bale silage it lifted about over a foot the first time to just about lifting the third time now not lifting at all ,would it below in oil how do I go about checking such and bleeding it I don't have any experience of any Zetor smaller than an 8011 I no I could change the lift pump on one them in about half an hour while simple
But don't know where it at on the smaller Zetor our is it a big job changing it what's the cost

Can any one help me out please

When sitting in drivers seat just look down at floor where the transmission top cover is and there it is just near enough towards the front. Just behind the seat you are sitting is the filling point it,s on top of the lift cover and consist of a large diameter circle with nut sure it,s cast aluminium unscrew it from lift cover and it reveals magnet and filter same arrangement that your power steering oil reservoir which is sitting in front of the radiator up front.
If you slide in under the tractor there is a large plate at rear of transmission with row of nuts I say in a circle might not be accurate description well pump is in there.