NH 270 timing problems

I have a new Holland 270 square baler that I'm having problems with it jumping time. I had been clear through this Baler several years ago and it usually runs like a sewing machine. Normally bale 500 to a thousand Bales a year with it. This year I replaced the main and knotter drive chains. It had got to the place where after about 200 or 300 Bales it would break a shear pin and I'd have to put it back in time. Dad went to bail some straw yesterday and today and now it will Bale about three or four bales, and then break a pin. I haven't had a chance to look at it yet, but I'm wondering where to start on it. Will definitely take a look at the tension on the drive chains. I counted the links off of the chain that I replaced so it is exactly like what was on it. I think that they were still the original chains. Just wondering where else I can look for a problem.

NH 270 timing problems