Iamanugget42

Try this (Assuming you are on windows): Open your roaming folder (By typing %appdata% into windows search or run) Go to '.technic' Delete the folder called 'tekkit' Launch tekkit classic from the launcher again. It may take a while; it will reinstall all files. **PLEASE NOTE: If there are worlds you'd like to save if you've played tekkit before, go into the 'tekkit' folder and copy the folder 'saves' to another directory, then paste it back in after tekkit has reinstalled**

Go into Options > Video Settings > Fullscreen, then click it so it says 'on'. It should then boot up in fullscreen mode from that point on. If you want to remove it from fullscreen mode, do the same thing to toggle it off.

Are you on a server? In single player? If you are on a server, are you right at spawn? By default spawn is protected, and you cannot destroy unless you are opped. If it's single player, are you in adventure mode? Holding any item in particular?

As Widgetos said, a certain upgrade or two may be draining the power. Try adding the kinetic energy upgrade, and see if the energy input is enough to replenish the lost power.

Good to hear you got it working.

Have you tried removing the anchors just in case? Having 8 anchors on the server is like constantly having 8 players on the server, which causes lag.