I just picked up a used Excal 1000 and since I have never owned one before, I have several questions. It looks like it has never been used. How can I determine the approx. age of it? How do I know when the battery is fully charged? I need to replace 2 missing knobs. Are the knobs that sell on eBay for 15.99 as good as any for replacement? Thanks in advance for your help and advise. I currently have a CTX 3030, but thought that this would be a good back up for me at the beach. The seller didn't know anything about it to help me out. My best help and advise has come from these forums.