transmission grinds after running for few mintues

[ACF]

have a husqvara m-zt-52 model 967177001, the owner tells me that hydraulic broke not sure when they found this out, they taped tank and added hydraulic fluid to tank and was told they vented the transmission. dropped off at shop was told that after running for few minutes there is grinding noise from transmission, this gives me the indication that the pump has gone bad, so looking for inputs if i am correct and is worth repairing the transmission since new one is 1400 dollars, looking for any inputs thanks