Attention Audio Aero Capitole owners, need help

I purchased a used Audio Aero Capitole mk1 about 1 year ago here on audiogon and the CDP just started making some large static sounds. Is it time to replace the tubes? Since I didn't receive a owners manual with the purchase how do I check the tubes? Where on the machine are they located? If I do need new tubes where are the best places to buy them?

Thanks for your help.