1974 ER 70 hp throttle/gear selector adjustment PLS help!!!

Hi I am new to the forum here,and very happy to finally find one lol. I have a (what I was told was) a 1974 70Hp evinrude,it has 3 cylnders if that helps. The control arm for the throttle will go into forward gear but when I try to shift it to reverse the shifter handle its self stops and will not budge in the backward motion for reverse. I did notice today that the shift handle was past the point of the neutral position for the motor to actually be in neutral. I hand checked by spinning the prop. I don't know if I need to adjust the cables at the motor or is my shifter messed up? The boat will also not start with the key but did start when I pull started it. jumped the starter and it engaged but only spun the motor slowly and every few seconds. I had a good battery, Any help will mean more than anyone knows I live rite on lake erie an sold my motorcycle to buy this boat so the whole family could enjoy the summer.

Sounds like the control box secter gears are messed up.-----------Easy to inspect by splitting the control box.---------Sounds like the starter needs to be taken apart for inspection.----------------And possibly you need to do more maintenance , like the water pump impeller before you venture out on a big lake.