gear slipping

I have just bought a new toy with a 1978 evinrude 25 . I have taken it out quite a few times over the summer with no problems but on the way to work on the blind last weekend it started sliping when I was taking off. I was able to hold the shifter foward to keep it from sliping, but it does not come all the way out of gear just a little miss and a know that it is not the engine because it will do it at idle and actually disengage to neutral. I do not have a maintenance book or a web site to refer to so any help will be great. I also can not figure out where to fill or drain the lower unit oil and if this my have something to do with it. thanks for any help

Re: gear slipping

The drain for the lower unit is below the bulge in the gearcase behind the prop. There is a similar vent screw higher up on the leg. Remove both to drain. Fill the unit from the bottom until the lub comes out the upper hole. Insert the upper screw first, then the lower. <br />If the unit skips at all, it is actually disconnecting and each time it does that, the clutch dogs suffer a little more wear. Your local library may have a service manual you can check out which will show you where and how to adjust the linkage. By the way, if any water comes out of the lower unit when you drain it, thats a sign of seal leakage and continued operation that way will eventually destroy the lower unit. Water is not a good lubricant.

Re: gear slipping

Thanks Upinsmoke I will drain and check the gear oil saturday, do you think the gear oil might have something to do with the slip