It could just need a good clean-lube-adjust, but the likelihood is a failure of the internal electronics that control this camera's shutter. You could take it to a repair shop for a quick inspection. Yashica parts are hard to come by unless the shop happens to have an old FX-103 to use for parts, which is unlikely. These cameras can go for as little as $40 on ebay, so repair may not be practicable.
I have not been able to use for a long time, but would like to again! HELP!!!!! Any suggestions?