Hi Lolly - Ive been using a pendulum for a few weeks now. I normally take the pendulum and close my eyes and see myself surrounded by white light and ask that I be procted by God and St. Michael the Arch Angel. I then ask that only higher beings and my spirits and guardian angel speak to me. It has seem to work for me and I havent had any issues. I then ask for the pendulum to show me its energy or ask the usual questions to get it tuned with me that day.
I hope you clean the pendulum and then give it a go. I have made my own charts as well as printing some free ones online. I saw a post by the King Of pentacles I believe and he wrote a few questions down in separate little pieces of paper and then shuffled them. he then put the pendulum over each paper and asked for the answer. That way he wasnt manipulating the answer. Just a thought. See if that works for you. Good luck and let us know how it goes for you.
I also never use mine for more that 20 min. It does take lots of energy. and make sure to clear your mind and focus on breathing when you do use it. :)