Printing using only the T-51 should not affect the feed at all. If the T-51 was set up properly, the press master cylinder will be locked out when it's operational control handle is in the night-latch position. This avoids the need to use a blank plate per "Old Guy's" suggestion. If the lockout is not functioning, you will need to do that as the image will transfer to the 9810's master cylinder.
It sounds like you are having feed problems without that only get worse when the t-head is used. The T-51 is a notorious water drippier. That is why it comes with a catch trey that sides beneath the water system. Fountain Solution dripping on the paper as it is fed is the only thing I can think of that might affect the feed. Air, vacuum, impression cylinder grippers and the buckle adjustment are the most common areas that cause feed trouble. There are other possibilities, but check those first.
The T-51 manual is an excellent resource. It contains the procedure for everything T-51. Good Luck.
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