i just got a 1872 with 60"deck,54"blade,2 stage snow blower.So i'm new to the 1872.So far i have did just the basic maintenance spark plugs,engine oil & filter,fuel filter,air filter,and hydro oil & filter.IMO i wouldn't let the aluminum rear scare you.When i changed the hydro oil in mine it was clean.Mine had 1470 hours on it and the hydo seems to be strong.I have been using the snow blower, no weird noises in the hydro it does not creep when in neutral.
It starts hard in the cold so i have to put a heater on it to get it running but once it is running she is smooth.It needs new spark plug wires and the starting trouble will have to be fixed.When snow season is over i will have to pull the engine.It smokes a little i am thinking and hoping just rings so while the engine is off i will replace and or take care of what ever it needs.