diff --git a/src/swiftest/swiftest_coarray.f90 b/src/swiftest/swiftest_coarray.f90
index e97488a0f..7dbd1a816 100644
--- a/src/swiftest/swiftest_coarray.f90
+++ b/src/swiftest/swiftest_coarray.f90
@@ -24,20 +24,33 @@ module subroutine swiftest_coarray_balance_system(nbody_system, param)
         ! Internals
         integer(I4B), codimension[*], save :: ntp
         integer(I4B) :: img,ntp_min, ntp_max
+        character(len=NAMELEN) :: min_str, max_str, diff_str, ni_str
 
         ntp = nbody_system%tp%nbody
         sync all
+        write(param%display_unit,*) "Checking whether test particles need to be reblanced."
         ntp_min = huge(1)
         ntp_max = 0
         do img = 1, num_images()
             if (ntp[img] < ntp_min) ntp_min = ntp[img]
             if (ntp[img] > ntp_max) ntp_max = ntp[img]
         end do
+        write(min_str,*) ntp_min
+        write(max_str,*) ntp_max
+        write(diff_str,*) ntp_max - ntp_min
+        write(ni_str,*) num_images()
+        write(param%display_unit,*) "ntp_min   : " // trim(adjustl(min_str))
+        write(param%display_unit,*) "ntp_max   : " // trim(adjustl(max_str))
+        write(param%display_unit,*) "difference: " // trim(adjustl(diff_str))
         if (ntp_max - ntp_min >= num_images()) then
+            write(param%display_unit,*) trim(adjustl(diff_str)) // ">=" // trim(adjustl(ni_str)) // ": Rebalancing"
             call nbody_system%coarray_collect(param)
             call nbody_system%coarray_distribute(param)
+            write(param%display_unit,*) "Rebalancing complete"
+        else
+            write(param%display_unit,*) trim(adjustl(diff_str)) // "<" // trim(adjustl(ni_str)) // ": No rebalancing needed"
         end if
-
+        call flush(param%display_unit)
         return
     end subroutine swiftest_coarray_balance_system
 
@@ -700,10 +713,8 @@ module subroutine swiftest_coarray_distribute_system(nbody_system, param)
 
         write(image_num_char,*) this_image()
         write(ntp_num_char,*) nbody_system%tp%nbody
-        if (this_image() /= 1) sync images(this_image() - 1)
         write(param%display_unit,*) "Image " // trim(adjustl(image_num_char)) // " ntp: " // trim(adjustl(ntp_num_char))
         if (param%log_output) flush(param%display_unit)
-        if (this_image() < num_images()) sync images(this_image() + 1)
 
         deallocate(ntp, lspill_list, tmp, cotp)
 
@@ -711,4 +722,4 @@ module subroutine swiftest_coarray_distribute_system(nbody_system, param)
     end subroutine swiftest_coarray_distribute_system
 
 
-end submodule s_swiftest_coarray
\ No newline at end of file
+end submodule s_swiftest_coarray
diff --git a/src/swiftest/swiftest_io.f90 b/src/swiftest/swiftest_io.f90
index 38b1735d7..eea186c48 100644
--- a/src/swiftest/swiftest_io.f90
+++ b/src/swiftest/swiftest_io.f90
@@ -416,9 +416,9 @@ module subroutine swiftest_io_dump_storage(self, param)
       associate(nc => self%nc)
 #ifdef COARRAY
          sync all
-         if (param%lcoarray .and. (this_image() /= 1)) sync images(this_image() - 1)
          write(param%display_unit,*) "File output started"
          call iotimer%start()
+         critical
 #endif
          call nc%open(param)
          do i = 1, self%iframe
@@ -433,10 +433,10 @@ module subroutine swiftest_io_dump_storage(self, param)
          end do
          call nc%close()
 #ifdef COARRAY  
-         if (param%lcoarray .and. (this_image() < num_images())) sync images(this_image() + 1)
+         end critical
          call iotimer%stop()
-         call iotimer%report(message="File output :", unit=param%display_unit)
          sync all
+         call iotimer%report(message="File output :", unit=param%display_unit)
 #endif
       end associate