DP 650 submersibles

[LynnCeeBee]

Both my DP-650's started functioning badly today, so I took them apart, cleaned them and checked the impellers. Everything seemed fine after that, but now, they don't start up at all. After searching and googling, I discovered that these pumps were prone to this problem of hard-restarting. Looks like I've done what others have done maintenance-wise, but what's the secret to getting them to start again? Help! ....do I need to buy new pumps???