Saving and re-applying symbology properties for classified raster in ArcMap?

Previously I have saved as a layer file and then imported the symbology from the layer.

To save as a layer file right click on the layer in the table of contents and select 'save as layer file'.

To import the symbology click on the open folder in the raster properties dialog.

then browse to the layer file saved to disc

Note: if the layer symbology is broken (the layer cannot be found) this may not work so well, the colours/symbols are imported but the ranges are not, reclassifying the raster will usually fix this; it is best not to let the layer get invalid if you want to use it again.