What you can do is to pull the stem out and get some heat proof packing grease. This is a virgin grease designed for water systems. Pull the bonnet off the stem and put a little grease on the arm above the stem that fits into the bonnet, then put a little more on the threads of the stem. Install a new rubber gasket as long as the stem is out of the hole. Then reinstall everything. I think you will find the faucet works much better. Make sure you do both the hot and cold sides. If you do not, you will wear out the gasket much faster, since you will apply the same pressure on the hot and cold sides; and if one side works easier it will be closed harder.