Puff Embroidery on Barudan

We have a 6 head 2002 BEDYHE-ZQ that we recently acquired, Its sews flats and hats great, But when I try to sew a puff design on cap, It has severe birdnesting in bobbin area,When it does sew , you can not see any bobbin thread on back side no matter how loose bobbin is,

Do I need to make any mechanical adjustments to machine before sewing puff,
raise presser foot height etc.

We have a couple of single heads , toyota and happy, the design sews fine on,

any input would be appreciated, This is first barudan I've had and not to familiar with them,

thanks mark