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Your pendulum does a complete swing in 1.9 seconds. You want to SLOW IT DOWN so it takes 2.0 seconds.
Longer pendulums swing slower.
You need to <em>make your pendulum slightly longer</em>.
If your pendulum is hanging by a thread or a thin string, then its speed doesn't depend at all on the weight at the bottom. You can add weight or cut some off, and it won't change the speed a bit.
The reason is because the molecules didnt come togeather around that time