This unit was already installed in a 20 yr old condo I bought, and I really like it...the problem is this; I want to use the self clean feature, but I don't know how; the directions on the stove say to set the timer after the oven is set for "clean", but the timer and clock are no longer operational. The oven will not self clean just by turning the knobs to "clean" and sliding the lock; apparently it needs the timer to actually start.