The problem is big! REVAMP YOUR INTERNAL RAINWATER SYSTEM WITH RIGS! No matter what system you have, weather it be Taylor fascia internal, Klass, Dimonds, Triline, Metalcraft, Norgate etc etc, they are all very similar with the same issues. They are well known to be problematic with multiple reasons for water ingress, from large holes in the gutters to bad design parameters, houses settling over time and embarrassingly, poor trade practices. Most of the machines that manufactured these products are obsolete now and even if you can find a product, the financials stack up against keeping internal gutter systems once there are signs of issues starting.