Hi Gary,
I took the gentleman's way out on this one and used my cheque book, this time I didn't physically do the work but I was there for all of it. A Yanmar trained technician took off both end caps, he also removed the turbo, oil cooler and the exhaust elbow as I was having a major service, including turbo recon,injectors, etc. @ 3000 hours.
I mentioned to him that I had tried to remove the heat exchanger last year and it didn't seem to want to move and I was reluctant to use force, so I flushed it with Barnacle Buster which lead on to seizing the gearbox when the transmission cooler failed. He simply tapped sharply a couple of times using a wooden circular plug from my emergency kit about 55mm in diameter, on the end from aft to forward and it moved, then he pulled it from the forward side and passed it up to me, easy as that. He told me that they are prone to sticking.
I helped put it back in and it simply slid into the casing and sealed on two O rings but they need to be new, then the end caps. He wouldn't tell me what they had used to clean it but it looked like brand new.
The Yanmar workshop manual shows how it draws out but offers no instruction.
For the previous six months or so I had been using a little bit of oil on long runs and this turned out to be yet another hole, this time in the engine oil cooler and it had to be replaced.
As normal, the diesel lab commented that I hadn't been running the engine hard enough, usually 2250 RPM. The correct revs for that engine are 2450 to 2650 RPM and there is no doubt since the service it has been running better than ever, although those extra revs increase the fuel usage to around seven litres per hour.
I hope this is of some help.
Regards,
Trevor