Lifter won't stay in adjustment.

[flathead4rd]

8-CM Merc engine. 296 C.I. 3-3/8 X 4-1/16. Potvin Cam and lifters. Lifter on #2 won't hold it's valve lash. I'm thinking of two options. #1 back the lifter adjusting bolt out as much possible and distress the threads with a small chisel or punch. #2 Use Red or Blue thread sealer on on the adjuster threads. I don't want to remove the head again if I can avoid it. Thanks .