I have the same issue. The problem lies not with your VCRs, but the antenna. It takes much more signal strength to record to a tape than to run the tuner in the VCR to watch TV. Also, antennas are directional and need to be rotated to where the transmitter is located. This can be quite difficult if you live in a valley, there are tall buildings in the way or for watching one program while recording another. You might have to bite the bullet and shell out for a subscription service (cable, satellite, fiber optic) to get a signal that will be consistent for all the channels you wish to record.
Adina Hirschmann, Proprietor: Component Connections, Bergen County, NJ, June 2007