Getting past 140kg mark. On all other areas my strength has increased and my bench is lacking. I have checked and double checked my form. I have switched from drop sets to 6/8 sets of 3 and I fail at 137/5 kg. Reps of 5 and 6 are doable at 128kg. Any suggestions should I stay at 128 and work on 5/6 sets of 5? I been stuck on this for about 6 weeks.

Bench twice a week