ILE service program questions

I created a module (named TESTMOD) and from that created a SRVPGM (named TESTSRV).  Then I compiled an RPG4 (named mainpgm) which uses a subprocedure in the SVCPGM.

The mainpgm points to a binding directory in the H spec as follows:

H dftactgrp(*no) bnddir('JRSBINDDIR')                              
                                                                   
D loadfield1      PR             6                                 
d  lf_input                     10                                 
                                                                   
D field1          s             10                                 
                                                                   
c                   eval      field1=loadfield1(field1)            
c     field1        dsply                                          
                                                                   
c                   seton                                        lr
                                                                   
                               

When I change the SRVPGM, the mainpgm still runs the old subprocedure.

Here is part of the compile listing of MAINPGM.  It appears that the binding is static, not dynamic.

                 E x t e r n a l   R e f e r e n c e s     
 Statically bound procedures:                              
    Procedure                            References        
    LOADFIELD1                                3       8    

Why is the subprocedure LOADFIELD1 statically bound, and not dynamic??  (Why doesnt it change when I modify the subprocedure and re-create the service pgm)?

All is on OS/400 v4r4.

How can I debug the sub-procedure using STRDBG?

Thanks!