Check to make sure the downspouts are not plugged with roots and dirt. Get someone to take a garden hose to the downspout and turn the hose on. And "make sure" U SEE where it is coming out at the bottom. Depending on the rain event "Amount of rain during a given time period" Gutter, partial clogged or smaller. Gutter can do spill over. We do not see this because we are inside most of the time.