diff --git a/firedrake/assemble.py b/firedrake/assemble.py
index dafe2a32ab..61909e9955 100644
--- a/firedrake/assemble.py
+++ b/firedrake/assemble.py
@@ -311,8 +311,7 @@ def __init__(self,
                  zero_bc_nodes=False,
                  diagonal=False,
                  weight=1.0,
-                 allocation_integral_types=None,
-                 needs_zeroing=False):
+                 allocation_integral_types=None):
         super().__init__(form, bcs=bcs, form_compiler_parameters=form_compiler_parameters)
         self._mat_type = mat_type
         self._sub_mat_type = sub_mat_type
@@ -322,7 +321,6 @@ def __init__(self,
         self._diagonal = diagonal
         self._weight = weight
         self._allocation_integral_types = allocation_integral_types
-        assert not needs_zeroing
 
     def allocate(self):
         rank = len(self._form.arguments())
@@ -1129,8 +1127,7 @@ def _apply_bc(self, tensor, bc):
         pass
 
     def _check_tensor(self, tensor):
-        if not isinstance(tensor, op2.Global):
-            raise TypeError(f"Expecting a op2.Global, got {tensor!r}.")
+        pass
 
     @staticmethod
     def _as_pyop2_type(tensor, indices=None):
@@ -1192,8 +1189,8 @@ def _apply_bc(self, tensor, bc):
             self._apply_dirichlet_bc(tensor, bc)
         elif isinstance(bc, EquationBCSplit):
             bc.zero(tensor)
-            get_assembler(bc.f, bcs=bc.bcs, form_compiler_parameters=self._form_compiler_params, needs_zeroing=False,
-                          zero_bc_nodes=self._zero_bc_nodes, diagonal=self._diagonal).assemble(tensor=tensor)
+            type(self)(bc.f, bcs=bc.bcs, form_compiler_parameters=self._form_compiler_params, needs_zeroing=False,
+                       zero_bc_nodes=self._zero_bc_nodes, diagonal=self._diagonal).assemble(tensor=tensor)
         else:
             raise AssertionError
 
diff --git a/firedrake/bcs.py b/firedrake/bcs.py
index f0d007ede4..7c6821b3e3 100644
--- a/firedrake/bcs.py
+++ b/firedrake/bcs.py
@@ -634,10 +634,10 @@ def reconstruct(self, field=None, V=None, subu=None, u=None, row_field=None, col
                 return
             rank = len(self.f.arguments())
             splitter = ExtractSubBlock()
-            if rank == 1:
-                form = splitter.split(self.f, argument_indices=(row_field, ))
-            elif rank == 2:
-                form = splitter.split(self.f, argument_indices=(row_field, col_field))
+            form = splitter.split(self.f, argument_indices=(row_field, col_field)[:rank])
+            if form == 0:
+                # form is empty, do nothing
+                return
             if u is not None:
                 form = firedrake.replace(form, {self.u: u})
         if action_x is not None: