8051 at cut
This does not sound right. The oscillator should have those capacitors.
I would check carefully the crystals, to make sure they are parallel resonant crystals and they have not been damaged (fractured). If they are AT-strip crystals, these can easily be overdriven. In that case, I would install 33pF caps, but from the output of the oscillator to the crystal I would connect a resistor. Typically, a few hundred ohms should suffice. (Actually the resistor's value should be equal to the impedance, in ohms, of one of the 33pF caps at the crystal frequency).
With HC-49 AT-cut crystals, you should have no problem running with 33pF.