OK I have a few questions
, first the simple things, the NOW start hard start , could very simply be from a BAD battery just cause it was charged and showing fully charged, doesn't mean the battery is good, it needs to be load tested to rule that out
as a battery with poor cells can show 12+ volts, yet be too weak to start machine properly
and as you said, check fuses as well and clean terminals and check all wire connections and wires themself!
NEXT as for water in oil, since you stated you had oil changed, then parked machine for expended periods of time not really using it
you really don't know much about it running wise or not
SO< some thoughts that come to me
any chance this machine was in a flood?
and was at some point flooded under water
I know of MANY places that had major floods the past decade, and know of many folks that got burned buying things that were under water at auctions and never declared
folks clean them up and sell them FAR away or likes to unsuspecting buyers!
and when folks DRAIN oil,. after a motor was filled, , you seldom get it ALL out, same with dirt and other crap washed in with any water!
talk to folks that play in the deep water and mud with atv's UTV, they sink things often ) I have many friends that play this game,
enough to know how water can sit in spots and takes a few changes to clear 100 % of water, it some times hides in low spots to just clings to oil on sides of things(typically it burns off when tun a while too, like condensation in oil tends too SOME TIMES, pending how much that is)
and you *(never get 100 % of other stuff though with a full tear down , and thats a FACT too)
but again, you stated you never rally RAN motor up to temp much or long enough to remove MINOR amounts!
and since you stated, you did a second oil change and LOTS of clear water came out
this again leads me to believe that water is getting in thru fill cap, or dip stick, or thru air box, as thats about the ONLY way your going to get LOTS of water in a motor without actually driving the machine in water to suck it in thru a vent or getting in thru fill points , when they went under water
I knew of some older machines that were known to have gaskets go dry at fill points and allow water to fill systems, be it motor or hydraulics
SO< that is for sure where I'd be looking hard
and from there oil lines
by chance is there standing ponding water in the machine any where, on top of floor, skid plates??
as again, some vent lines can suck water in thru them that way, or a line with a hole in it laying in water??
skid steer are famous(as most HD equipment) for belly pans to fill with debris and block drain holes!
which can lead to ponding water in them!
ANy how