Pfaff power quilter p3 having trouble setting pattern box its tells me my patern box is too small

I searched but did not see a service manual for that model using https://www.google.com

You might try asking Pfaff if they can provide it to you, although that is not guaranteed.

http://www.pfaff.com/en-US/

Search for:

Make Model error code p3

Perhaps the manual would be helpful:

PFAFF creative 7570 Instruction Book

According to the following web site, the feed dogs do not drop on this machine, Instead, there is a plate that covers the feed dogs:
Fluffy Sheep Quilting Do you have one of these Do you like it

Also thought this was interesting:
Oiling the PFAFF Grand Quilter 1200 Bernina Sewing Center Tampa

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1 - Thread the machine absolutely correctly (pages 25-26 of your instruction book)
2 - Balance the tensions (pages 29-30 of your instruction book)

contact Pfaff website about a manual or try youtube for a video

The free one came in the box with the machine, a replacement can be ordered...
PFAFF Model GrandQuilter 18 8 Users Instruction Manual PFAFF Model...

Pfaff Support will help you

Hello

If you have changed the needle and rethreaded the machine, then take apart your bobbin and make certain there are no small pieces of thread or lint in it. Check your tension. Do you have an automatic thread cutter? I had the same problem and it was because my automatic thread cutter was cutting the thread too short. Some how the cutter had gotten bent...I could not tell it, but it was.I put the blade of a flat head screw driver under the cutter and GENTLY bent it back down. Fixed the problem. Works perfectly.

Speak to the Pfaff dealer where you bought it and tell them....they will probably arrange a replacement with little fuss.