i've got a little korg metronome that does the same thing. However, it seems to take the distance between two distinct beats rather than averaging over a few. Makes it a little hard to zero in.

I use a drum machine on live performances.
When we play with just the three of us ( accordion, fiddle, guitar ) we use the drum machine.
Jude

Any recommendations on a simple to use, inexpensive drum machine that will allow easy programming of waltz & 2-step beats? We have an old Boss 505 that is so complex to program that it sits in a cabinet drawer unused....

I practice a lot with a drum machine and have also used it playing out with the Bluegrass Band when we do some cajun and Zydeco. First, it will really help you improve and cleanup any timing problems. Secondly, if I can program a Boss 505 believe me anyone can. Just work your way through the instructions and keep it simple. I put in a double clutch Zydeco beat and a waltz and use them all the time. I put in the double kick and the snare and it works fine to practice Zydeco. Same with the waltz; just a bass on the one and snare on two and three. Very simple and sparse but that's all you need.

Drum machines and metronomes a very valuable tools; but the one thing -- the *one* thing -- that will improve your timing is your left hand. (Assuming all of us play right-handed; yes, Lil Guyland Leday is excused ;) Play them frogs. Play 'em till you get 'em down pat. When you do, the right hand will fall into place and accelerate your learning. I'm still trying to get 'em down. It ain't easy and it can be frustrating. Don't give up.