Advice, Please!

A new broom sweeps clean,

but the old broom knows the corners.

~ Irish Saying

So, I've got an 11 year old, mid-level mechanical Kenmore sewing machine.  Truthfully, it's done right by me over the years...  I think of it like a little work horse - nothing fancy and a little bit noisy, but it keeps going and going...  

It definitely needs a tune-up - it is starting to give me problems with the tension and the buttonhole does NOT work well at all anymore.  Each tune-up costs about $100, so 3 or 4 tune-ups and all of a sudden you're looking at the cost of another machine...  

So, I'm wondering what I should do.  Should I take it in for another tune-up or should I start shopping for a replacement machine - and maybe move up a notch or two in the sewing machine hierarchy?  

Actually, the thing I most want advice about is the mechanical versus computerized decision.  I have this sense that mechanical machines are more reliable and cheaper to repair and computerized machines are more finicky and expensive to repair.  (Of course, I still drive a manual transmission car, so that tells you something about me!)  

Am I right or am I out of touch?  Whenever I upgrade - now or several years from now - should I stick with a mechanical machine or should I "get with the times" and go computerized?  Any and all advice will be greatly welcome!  Thanks!  :)