Had to do the fan blower motor on my old 240. Tis a PITA. I couldn't find a matrix. Spoke to Tony, The Old Volvo Man Barret at Brookhouse. He advised 'if it ain't broke......'. I took it out and flushed it through and clean water came out. So did as advised and stuffed it back in. That was three years back.
Hopefully yours will be in a similar state.
So I wouldn't worry too much .
Hi James, Nissens are very good aren't they. The one I put on Tank in 06/7 still looked new when I sold in April this year .