Jamome RX 18S - feed dog problem

Question

Hi there, I have an Janome sewing machine which is about 8 years old. It has been sewing fine all these years in fact it has not been used very frequently only for simple tasks like some pant hemming and the like. Last time I was using it I had a problem with my feed dogs - I couldn't get them to go back up. This is where my problem gets a bit tricky because this happened about a year ago and the details about what actually caused the problem in the first place are now a bit foggy. The machine has been sitting now for almost a year.Today I took off the needle plate and cleaned that area. I also opened up the bottom to have a look. I think this problem will be easily fixable except I am not sure how it is supposed to look in there. I am thinking there might be a piece missing or something that just isn't catching properly. Any ideas? Any leads on where to go for a diagram of the inner workings of my machine? Like I said it looks like a simple repair, but I am not sure what I am doing. Obviously I don't want to make the situation any worse than it already is. Thanks for any help you may have to offer...