Leaking oil past the "O" ring - which seals the two halves - in the left front area. This has been noted on "high time" machines. The rectification is to maintain accurate flight records.
	Deterioration of the main transmission "rubber" mounts leading to unusual vibrations and machine with hard to isolate vibrations. This is usually caused by the use of strong cleaning fluids ranging from Avgas to strong degreasers. Use only mild detergents to wash off dust accumulations etc.
	The main rotor shaft internal attach nut unscrewing and then forcing the main rotor shaft up, breaking the top transmission bearing retainer and swashplate tube. The main rotor remained attached by the control tubes.
	Early machines had illumination of the chip light by particles from the input quill Timken roller bearings.
	Cracking and breakage of the left hand chrome molly transmission frame - usually on the left hand side between the two main attach bolts. Hard to see when conducting a daily inspection in bright sunlight. Use a torch in the evening or early morning to inspect this area.