Can the oil pump be opened for cleaning and repair or is a sealed unit. on 1994 BMW 740i

I recently purchased this car. The warning light was frequently on while driving. The engine is being removed and opened for cleaning (110,000 kilometers). The sludge and baked on deposits on the sump pan and valve covers are so bad that the agent doesn't think flushing is a good option. The filter when removed was dripping black oil like thick honey. Obviously the engine had not had oil and filter changes or servicing for a few years.

Asked by for the 1994 BMW 740i