I have had a yoder 640 for 5 years now and have had nothing but problems the the temp accuracy its always of by 50 degrees, I have also had on numerous times when you turn it on the digital temp goes wacky it jumps around from 140 to 225 to 400 to 350 all in a matter of 20 seconds and will not reset even when completely unplugged. Yoder's answer is always change the temp probe. well obviously this has not worked (4th time). so its sad to say I can no longer recommend Yoder (and I do like it when it works) and I will have to purchase a different brand. Dave Tualatin OR