If you have purchased one of Apple’s new 12-inch MacBooks (Early 2015), then be aware of a potential keyboard issue where the space bar may not respond, especially when pressed on the left or right edges. When this happens, the bar will feel as if it has hit the bottom of its range without sending the keypress to the system. Additional force may ultimately activate the key, but with standard typing this problem may make it difficult for affected users to enter spaces.
Despite this, affected space bars will usually work when pressed in the center. This along with additional pressure activating the key suggests the issue is a mechanical one, meaning that it cannot be addressed by a software or firmware update. Therefore, instead of adjusting your typing habits to accommodate this problem, be sure to take advantage of your Mac’s warranty and bring the system in for servicing.
This problem might affect a large number of systems, or may be only with a few that came off one or two production lines; however, regardless of its extent, Apple will likely be very eager to investigate the issue and correct it, especially for one of its newest products. Therefore, you should have no problem in contacting Apple for an exchange regarding this or any other obvious defect in your new MacBook.
Since this problem may be inherent to the keyboard design on the MacBook, be sure that you thoroughly test any replacement (though this particular issue will likely present itself, given the space bar is so commonly used). Be sure to retain all documentation for your purchase and servicing.