Is this something l can fix or do l need to take it to the garage?

150ccs alcohol by drip plus the Kiss of Life.

As in the whole wiper does not move? This sounds the same as just happened to my dads car. A nut that holds the wiper to the motor arm had come loose. We tried to fix it but our fixes only held for a day or two. In the end it needed a new motor assembly.

had same with drivers side wiper on daughters punto turned out to be small arm had popped off
open bonnet and check near bulk head see if you can feel arm hanging loose should pop onto a ball at end of wiper arm takes some squeezing to get it to pop back on took about 15 mins but has been ok since

l think this may be due to a broken linkage of the wiper. You have to take it to the garage.