diff --git a/tests/debug/Test_8888.cc b/tests/debug/Test_8888.cc
new file mode 100644
index 00000000..279bc8bd
--- /dev/null
+++ b/tests/debug/Test_8888.cc
@@ -0,0 +1,118 @@
+/*************************************************************************************
+
+    Grid physics library, www.github.com/paboyle/Grid 
+
+    Source file: ./tests/Test_general_coarse_hdcg.cc
+
+    Copyright (C) 2023
+
+Author: Peter Boyle <pboyle@bnl.gov>
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License along
+    with this program; if not, write to the Free Software Foundation, Inc.,
+    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+    See the full license in the file "LICENSE" in the top level distribution directory
+    *************************************************************************************/
+    /*  END LEGAL */
+#include <Grid/Grid.h>
+#include <Grid/algorithms/iterative/ImplicitlyRestartedBlockLanczos.h>
+#include <Grid/algorithms/iterative/ImplicitlyRestartedBlockLanczosCoarse.h>
+#include <Grid/algorithms/iterative/AdefMrhs.h>
+
+using namespace std;
+using namespace Grid;
+
+int main (int argc, char ** argv)
+{
+  Grid_init(&argc,&argv);
+
+  const int Ls=8;
+  const int nbasis = 40;
+  const int cb = 0 ;
+  RealD mass=0.01;
+  RealD M5=1.8;
+  RealD b=1.0;
+  RealD c=0.0;
+
+  GridCartesian         * UGrid   = SpaceTimeGrid::makeFourDimGrid(GridDefaultLatt(),
+								   GridDefaultSimd(Nd,vComplex::Nsimd()),
+								   GridDefaultMpi());
+  GridRedBlackCartesian * UrbGrid = SpaceTimeGrid::makeFourDimRedBlackGrid(UGrid);
+  GridCartesian         * FGrid   = SpaceTimeGrid::makeFiveDimGrid(Ls,UGrid);
+  GridRedBlackCartesian * FrbGrid = SpaceTimeGrid::makeFiveDimRedBlackGrid(Ls,UGrid);
+
+  ///////////////////////// RNGs /////////////////////////////////
+  std::vector<int> seeds4({1,2,3,4});
+  std::vector<int> seeds5({5,6,7,8});
+  std::vector<int> cseeds({5,6,7,8});
+
+  GridParallelRNG          RNG5(FGrid);   RNG5.SeedFixedIntegers(seeds5);
+  GridParallelRNG          RNG4(UGrid);   RNG4.SeedFixedIntegers(seeds4);
+
+  ///////////////////////// Configuration /////////////////////////////////
+  LatticeGaugeField Umu(UGrid);
+
+  FieldMetaData header;
+  std::string file("ckpoint_EODWF_lat.125");
+  NerscIO::readConfiguration(Umu,header,file);
+
+  //////////////////////// Fermion action //////////////////////////////////
+  MobiusFermionD Ddwf(Umu,*FGrid,*FrbGrid,*UGrid,*UrbGrid,mass,M5,b,c);
+
+  MdagMLinearOperator<MobiusFermionD, LatticeFermion> HermOp(Ddwf);
+
+  
+  std::cout << "**************************************"<<std::endl;
+  std::cout << "         Fine Power method            "<<std::endl;
+  std::cout << "**************************************"<<std::endl;
+
+  LatticeFermionD pm_src(FGrid);
+  pm_src = ComplexD(1.0);
+  PowerMethod<LatticeFermionD>       fPM;
+  fPM(HermOp,pm_src);
+
+  
+  std::cout << "**************************************"<<std::endl;
+  std::cout << "         Fine Lanczos  (poly, low)    "<<std::endl;
+  std::cout << "**************************************"<<std::endl;
+  
+  int Nk=80;
+  int Nm=Nk*3;
+  int Nstop=8;
+  int Nconv_test_interval=1;
+  
+  //  Chebyshev<LatticeFermionD>      IRLChebyLo(0.2,64.0,201);  // 1 iter
+  Chebyshev<LatticeFermionD>      IRLChebyLo(0.0,55.0,101);  // 1 iter
+  FunctionHermOp<LatticeFermionD>    PolyOp(IRLChebyLo,HermOp);
+  PlainHermOp<LatticeFermionD>          Op(HermOp);
+
+  ImplicitlyRestartedLanczos IRL(PolyOp,
+				 Op,
+				 Nk, // sought vecs
+				 Nk, // sought vecs
+				 Nm, // spare vecs
+				 1.0e-8,
+				 10 // Max iterations
+				 );
+
+  int Nconv;
+  std::vector<RealD>            eval(Nm);
+  std::vector<LatticeFermionD>     evec(Nm,FGrid);
+  LatticeFermionD     irl_src(FGrid);
+
+  IRL.calc(eval,evec,irl_src,Nconv);
+
+  Grid_finalize();
+  return 0;
+}