Mint Beocord 2400 Reel-to-Reel 1/2 Track

Hello dear b & o community.

I am now the proud owner of a completely restored beocord 2400 1/2 track tape recorder reel to reel. The mechanic called today. I can pick it up next week. The mechanics have been completely overhauled and the boards have been partially renewed and measured. However, the tape heads do not achieve the expected frequency response. Logical, since the heads are now 50 years old. I would like to convince myself of the best possible quality of an ordinary tape recorder, where I would be if I asked!

Can someone tell me where I can find a suitable replacement?

or are there other manufacturers' heads that will fit?

Revox, studer, ...!

Will run it on the beosystem 7000 with beogram 9500, penta 3 and a restek miniria + phono preamplifier.

It it possible it's not the heads but that the deck isn't biased right for the kind of tape you can get nowadays?

the machine is attuned to maxell. I gave him one of three tapes sealed in. I'm sure I'll buy new belts over time and adapt the machine accordingly. i am very familiar with the mechanics. I think I can do it.