If it is requiring you put a lot of pressure to make them work, it sounds like those keys are going to need replacing, and possibly the whole keyboard (depending on that models setup).
First try this...
1. Uninstall the keyboard driver.
2. Reboot the computer (without reinstalling the driver).
3. When it restarts, it should reinstall the driver on its own.
If this doesn't fix the issue, you may wish to try connecting an external keyboard and see if it works fine. If it does, then I would look at the key/keyboard replacement.