1998 Volkswagen Polo wiper water pressure and intermitent rear wiper

Some washer bottles have a filter on pump which choke up and restrict water .If not that , washer pump / motor knackered .The parking mechanism for the wiper is usually inside motor .

Thanks. If I try a good old fashioned method of shoving a hosepipe on a strong jet in the water container could it clear it? Don't think the motor is knackered as there is some water coming out - just not as much as there was before - I know naff all about cars!

You could try that , might work , just be careful you don't knock washer hose off with too much pressure . If it's easy to access w/screen washer bottle then you can remove it and check / clean pump , blow through water pipe. Again if blowing through water hose , go easy or you will blow it off at jets or any junctions . Some bottles are very awkward to remove , can't remember where yours is fitted .