My trim gets up about half way and starts to struggle to go all the way up I have to assist it.I checked batteries made they were charged check,than put grease in all grease points around motor,now I wanna try an add trim fluid but I can't figure out where it goes it's and old 1978 70 hp Johnson seahorse.Any advice would be appreciated.

look for a cap /w a flat head top to it. Should usually need a larger flat head to open the cap. There should be a fill cap near the cylinder area. Don't just dump fluid in and call it good. You're going to have to bleed the lines and fill/bleed fill/bleed a few times. There's dozens of videos on youtube on how to do it. 

Thank you I really appreciate it!!