PROBLEM DESCRIPTION: After applying IBM maintenance which introduces new DEBCHK ADDLOCK/UNLOCK function, APAR OA53955 (Z/OS 2.3) or OA55315 (z/OS 2.2 and lower), jobs using SUBSYS=LAM fail with DEBCHK errors :
IEC141I 013-DC,IFG0198N,............ DEBCHK=(00000008,00000403)

My question is can SO04128 ptf be applied across all LAM subsystem  even though IBM maint is applied,and we aren't getting the DEBCHK error?

z/OS 2.3 with APAR OA53955 
z/OS 2.2 and lower with APAR OA55315

Yes, you should apply SO04128 to all your Librarian systems even if they are not experiencing the abend.