Sooner or later almost every '107' SL owner will have to confront THE LEAKAGE ISSUE.
There is a design fault with this model which causes water to leak through the front windscreen drainage grill through the heater box or bulkhead into the interior front foot wells.
The problem is caused by the original drainage being inefficient and subsequent water build up causing corrosion , while the later models were slightly less prone to this fault it is now appearing on even the last 1989 models.
There is no easy fix.
Firstly the car needs to be investigated to rule out leakage through the screen.
Having ruled that out there are limited options.
1) Try to seal corrosion with appropriate sealers. Success rate: Minimal, might last a winter.
2) A proper repair involves removing the engine and virtually rebuilding the bulkhead . Success rate: Good but hugely expensive even then some cars stubbornly spring another leak.
3) Don't take the car out in rain, garage it at night or cover it with car cover. Success rate 100% (Tricky in England)