Honda 150 will not turn

I have a 2009 Honda 150 with 950 hours on a Wellcraft 21. It has been virtually trouble free until a couple of month whe we started to have problems starting the engine. We thought it was a battery problem or electrical cables issues. We changed the starting cables and batteries and even overhauled the starting motor. This weekend we tried to star the engine and the starter was not able to turn the motor, in only gave a clicking sound. We took the cover off and manually rotated the engine. It was hard as hell. We removed the plugs and poured some diesel and oil on it and still it was very hard to turn. I have moved by hand diesel engines that were easier to turn. The engine is not completed sized but it is not getting any better.The motor has not been overheated. When I turn it in gear the propeller turns and there is no noticessable noise . Could it be the water pump ?What should I be looking for.?. Any help could be greatly appreciated.

check the lower unit to see it there is any oil in it

Water in the lower unit / possibly ice now ?---No location posted so just a wild guess.

Remove and check sparkplugs for signs of water intrusion, check engine oil for water, if signs found in either it will need to be dismantled, if none found, remove gearbox and see if engine turns freely, if so gearbox will need further investigation

OK, last saturday we were able to pull down the lower unit. It was a real PITA, but we managed. The good news is that the powerhead is ok , the started was able to turn the engine normally. At first glance it appears that the problem was in the mid shaft bushing that was sizing the engine shaft.The bad news is that when we removed the bushing a piece of the base broke off. I am considering NOT to install a new one. We did find some scoring on the metal housing of the water pump that was damaging the impeller. I am ordering a complete water pump kit. The other thing that we found was that the lower unit oil was very low, but what was left of it was clean with no metal particles on it. I suspect the oil and water seals are compromised. We are changing them as well. Considering that the engine has 950 hours and is a 2005 model, I should count my blessings. Note to Myself: drop the lower unit at least once a year !
Regarding the dam lower unit shaft bushing, I read either on this Forum, or in another one, that its importance it is not quite clear. Iwill try to install a new one, but if it does not hold I am diching it. I do not want to spend over US$ 700 for the extension module where the bushing seats. Specially with an engine of this age. Thanks everybody for their imput.

Hi Piripucha, I changed the mid shaft bushings myself on my engines just for safety, not really dificult with a blind bearing puller and clippers for the circlip. Would not feel confortable not installing as medium/long term wobbling effects of the shaft could cause other damage and the bushings are not expensive. Be sure to remove all salt deposits from housing and to lube outside of bushing before installation, if not it can be a pain. Ref gearcase, 5 water entry oil exit points: oil drain screw, oil level screw (be sure to always replace orings and that they sit right at the bottom on the step of the screw) prop shaft, shift shaft and main shaft, at least on the BF200. Hope this helps.