I don't have one of those guns, but it is quite possible that there should be a guide. With the slide off, look in the front of the frame and see if there is a hole about the same diameter as the recoil spring*. If so, it is probably for support of the recoil spring guide. If you conclude that one is needed, it could probably be made by turning down a plain old nail and cutting to the right length.
*In firearms terminology, the "main spring" is the hammer or striker spring that fires the gun, even though other springs may be larger.