[Techman]

Funnily enough I've just been working on a similar small portable record player with a transistorised amplifier which needed cartridge replacement and mechanical work to the deck and while on test last Thursday, the amplifier suddenly failed half way through a record. Initially there had been some low level background crackling which had qickly cleared up by itself and had successfully played quite a few records over a few days. On switching it off and making a few checks to cartridge connections etc. (I had noted that there had still been a very slight hum from the speaker indicating that the main part of the amplifier was still working), I switched it back on and found it was working, but soon cut out again after a short time. Further investigation found that the first amplifier stage transistor immediately after the volume control had developed a dodgy base emitter junction (abnormal voltages and higher than normal forward resistance when removed and tested). This was one of the infamous BC148 'lockfit' types and and having opened a fresh a pack of RS Components BC108 transistors from my ancient stock and fitted one of these, all was back to normal operation.

So it sounds like it could well be the same amplifier stage in your amplifier that's causing the fault and a BC108 will work just fine.