SBC HMR to update contact header - failing

INVITE has
Contact: sip:eatf.ims.mnc370.mcc311.3gppnetwork.org:5060
P-Preferred-Identity: sip:35603111-003271-0@10.188.x.x>

I need to update the "Contact" header as follows
Contact: +sip.instance="urn:gsma:imei:sip:35603111-003271-0>"

Here is my HMR
header-rule

            name                                    extract_imei

            header-name                             P-Preferred-Identity

            action                                  store

            comparison-type                         pattern-rule

            msg-type                                any

            methods                                 

            match-value                             

            new-value                               

            element-rule

                    name                                    imei1

                    parameter-name                          

                    type                                    header-value

                    action                                  store

                    match-val-type                          any

                    comparison-type                         boolean

                    match-value                             sip:\d{8}-\d{6}-\d

                    new-value                               

    header-rule

            name                                    replace_contact_with_imei

            header-name                             Contact

            action                                  replace

            comparison-type                         case-sensitive

            msg-type                                any

            methods                                 INVITE

new-value "+sip.instance="<urn:gsma:imei:$element.imei1>""