Bosch distributors are found on many different cars and are generally very reliable. But after a high mileage you may find that the engine isn't running quite as it should. If the rest of the fuel and ignition system is well tuned but the car doesn't accelerate cleanly, the problem may lie in the distributor advance mechanism. Read more
On some distributors the baseplate simply lifts out, but on others it is sealed in. If the plate is sealed you can gently lever it out with a screwdriver in the access hole, but take great care not to damage the plate or distributor body. Note which way round the plate fits.