Is there any sense trying to fix the actual pump in a pressure washer or just get a new pump on EBAY. This one does not seem to be cracked, it just does not put out much pressure at all. New pump is under $100 delivered.
You might try cleaning out the hose outlet filter screen. It might be clogged reducing the pressure. It happened to ours.
Our son found that an electric replacement pump cost just slightly less than a new washer. Might want to check out replacement parts costs for your particular model.