I used the little blue pump to drain the water from my manifolds, etc on my 496HO. Only one of the green buttons came out. But I pumped until the pressure was great enough to pop the valve normally used to bleed the pressure off. Do I need to hold the valve down (closed) and put more pressure to get the other side to pop out? I tried tapping - in case it was stuck, but it still didn't pop out.

It worked fine last year. Is there another way to drain the system. I think I read that there are several plugs that can be removed also to manually drain the system.

Which side didn't pop? Did you look to see if water was indeed draining out of the side that didn't pop? If no water drained, you have a leak preventing that side from building pressure.

I could hear water draining, but didn't look close enough to see if it was from both sides.

It sounds like we may have boating weather this weekend again, I'll check more closely to see if both sides drain. We don't normally get extended cold weather to worry about freezing, but I will be out of town for a month and don't want to be worrying about it.