Newcaddy,
Fishing leadcore takes practice, getting used to it, and knowing where your lure is in the water is the key to success.Especially when fishing for laker's.Large laker's very rarely venture out of the depths,and thats where you want your lure.Just off the bottom.If your trolling in 40,50,or 100ft, you want to be just off the bottom.If your not getting snaged or picking up weeds your not deep enough.Trolling very,very slow,the slower you row the more your line will sink.
Trolling in 100ft of water with your lure at 40ft will not catch lakers,you might get lucky,but more often than not you'll get skunked.In mid to late april,depending on the weather,the lakers come to the surface,and can be caught just flat lining.They stay up for about a week depending on temps, 59 seems to be there limit.Good luck!