I can't get a par of camlocks to fit when engine is at TDC. Inlet one is nearly on but only fits after I'm off TDC and then exhaust camlock is way off. The engine no on the body plate is AR321.04 but i''ve tried 2 camlock kits an AST and a variable Sealey Alfisti one with multiple setting plates and I'm getting nowhere despite them being approved for that engine code. In the AST one the previous owner who was mechanic, had erased in the instructions the reference it could be used for my engine no. I'm at a loss to know how to sort this would be grateful for advice.