My mother-in-law gave me her DeLonghi CT-14, 4-slice toaster which is in pretty good shape with the exception of one flaw. The 2 slots on the left work as they should, but the 2 slots on the right, although the elements heat, do not hold when pushed down making them essentially unusable. The toaster doesn't have a manual, so I am kind of at a loss as to how to remedy the problem. Can you help?