Well, it has had two main dealer services in the last 7 or 8 months. No evidence of a service between 2011 (if I’m reading that right) and 2018. That doesn’t mean it hasn’t been serviced or at least had oil changes undertaken by a previous owner / independent, just that the service book hasn’t been stamped. I would ask the dealer the specific question about whether it’s had transmission fluid and filter changes and see what they say. If they cannot give you a definitive answer then it may be that the transmission fluid has not been changed for 65k miles / 6 years. Personally that would concern me. A lot. Then again, you could buy it and even though there have been no fluid changes the gearbox might never cause you a problem. Who knows? However, if it were to give you problems, you might kick yourself for not taking notice of the lack of proof that the powershift services had been carried out. I think a new replacement powershift box is in the region of £5k Worth bearing in mind. Don’t get me wrong, I think the powershift box is great...if properly serviced.
What warranty is the dealer offering? If they agree to 12 months and you get written confirmation that that would specifically include powershift related problems, well that at least gives you some peace of mind. At the very least I would insist on a fluid and filter change, with paperwork provided, before buying.
Sorry I can’t answer the question about whether or not to buy it; that has to be your decision, but hopefully my two penn’orth has given you some things to think about.