Not that I've already spent hours fixing leaks of coolant on the V8 and with an MOT looming I had the recurring issue of one wiper jet just not working.

The pump seemed ok and I checked for leaks but couldn't find anything. The driver's side jet kept blocking up.

This time I took a hose pipe, I've no idea how to remove the tank without silly work...and stuck it to flush out the said tank.

Now I had very little water pressure. So I agitated the tank bottom, sides and any where else by wiggling, scraping and turning the hose end. Whilst it was slow, some impressive jelly and bits floated up and out over the top. I kept this up for a good 30 mins until clear.

I turned the tap off which siphoned out the water so I feared a leak! Taking a jet clearing tool...a long dart like spike, I speared the jet firmly a number of times.

A dribble turned into a full spray so I repeated windscreen cleaning to flush out and clear any debris.

There are no leaks and the MOT was won albeit with some minor advisories. 

If your pump is working but your jets are blocked...this is a simple and worthwhile fix. 

I had a similar problem with my X Type a few years ago. I took the pump out of the bottom of the tank and flushed it out with a hose. The tank had blue fibery material in it almost like wet paper which was blocking the jets. I suspected cheap or old washer fluid but filled up with fresh fluid and didn't have any more problems..