I’ve got a 83’, 90hp V-4 that has been sitting up for a year while restoring the boat it is on. When I tried to start it recently it turns over very slowly and will not start. Tried several different batteries to make sure it wasn’t just a weak battery to no avail. With spark plugs out it will spin over fine, but with them in it barely turns over. I also tried to spin it over with a pull string off the flywheel to see if it might be the starter and found it very difficult to turn over that way. Could the engine just be gummed up due to sitting up for for a year? Thanks in advance for your help.