Removed the vacuum jacket and radiation shield and had a look through the window. Ops, sample debris stuck on the diffuser ring, it does not come out by tilting and shaking the cryostat. Removed the window and the debris material. The material is magnetic at liquid nitrogen temperature.
Diffuser and original kapton window were cleaned and put back on using 0.040" indium wire. Leak check was ok and diffusion leak rate through K-window was about 3E-6 t.l/sec.