Its worth getting new heavy duty nuts and hard washers and refit them one at a time followed buy re torqur all 1600 and mk1 use the small 3/8 studs torqure is 42 -46 lbft
on all the washers deform and you loose torque and clamping and std nuts just strip.
remove a nut and look at the washer surface it will be deformed .
Most suffer from some seapage from the rocker feed in the lh rear corner
the 1600 uses a thin steel shim gasket , not a copper or composite