element settings for Tom Chandley deck oven

hi there - have recently got hold of a reconditioned tom chandley...its pretty old (1990s I reckon) but works ok just wondering on top and bottom element settings for hearth based breads. I bake straight on the stone and am currently setting bottom to 3 and top to 3  - the breads are fine but I think i could probably go more, perhaps 4 - 5 on bottom and 4 on top. Does anyone have any advice. just want to maximise colour and spring without drying out crumb (which can happen if top is too low) thanks in advance