I would check your oil pressure next, if it is excessively high, it could conveivably cause the filling of the area around the jackshaft with oil and push it up the dizzy body between shaft and spindle, all in theory never seen it happen, at the end of the jackshaft ther eis a hole where the pressurised oil comes out, it travels down the jackshaft which is hollow from the front bearing to the rear bearing then out.
tabetha