Not sure what happened to your email, but the price for a PF-6 exchange is $75 plus shipping charges. The preamp card will be either repaired or replaced with a rebuilt one.
When you ship it, send the card in a static-safe bag and then pack the bag in a sturdy box. Insure it for $350 (replacement cost) and send it to:
Alembic
attn: repair
3005 Wiljan Court
Santa Rosa, CA 95407-5702
USA
Enclose a note that includes your return shipping address, the serial number of your Series I, and credit card payment details. Servicing takes 1-2 weeks plus transit time.